Webasto Air Top 2000 S D User Manual

List of Contents

Air Top 2000

Air Heater

Air Top 2000 S D (Diesel)

Air Top 2000 S B (Gasoline)

Service and Repair Manual

– Improper installation or repair of Webasto heating and cooling systems can cause

fire or the leakage of deadly carbon monoxide leading to serious injury or death.

– Installation and repair of Webasto heating and cooling systems requires special

Webasto training, technical information, special tools and special equipment.

– NEVER attempt to install or repair a Webasto heating or cooling system unless you

have successfully completed the factory training course and have the technical skills,

technical information, tools and equipment required to properly complete the

necessary procedures.

– ALWAYS carefully follow Webasto installation and repair instructions and heed all

WARNINGS.

– Webasto rejects any liability for problems and damage caused by the system being

installed by untrained personnel.

Air Top 2000 S

List of Contents

Introduction

1.1 Scope and Purpose.................................................................................................................................101

1.1.1 Use of Air Heaters.......................................................................................................................101

1.2 Meaning of Warnings, Cautions, and Notes............................................................................................101

1.3 Additional Documentation to be used......................................................................................................101

1.4 Safety Information and Regulations ........................................................................................................101

1.4.1 General Safety Notes..................................................................................................................101

1.5 Legal Provisions for Installation...............................................................................................................102

General Description

2.1 Combustion and Heating Air Fan ............................................................................................................201

2.2 Heat Exchanger.......................................................................................................................................202

2.3 Burner Insert with Combustion Tube.......................................................................................................202

2.4 Control Unit / Control Circuit Board.........................................................................................................202

2.5 Flame Sensor..........................................................................................................................................203

2.6 Glow Plug ................................................................................................................................................203

2.7 Temperature Limiter ................................................................................................................................203

2.8 Dosing Pump...........................................................................................................................................203

Functional Description

3.1 Functional Description Air Top 2000 S .......................................................................................................301

3.1.1 Control Element ..........................................................................................................................301

3.1.2 Switch-On....................................................................................................................................301

3.1.3 Stabilization.................................................................................................................................301

3.1.4 Heating Operation.......................................................................................................................302

3.1.5 Control Operation........................................................................................................................302

3.1.6 Control Idle..................................................................................................................................302

3.1.7 Switch-Off....................................................................................................................................302

3.1.8 Switch-Off upon Failure...............................................................................................................302

Technical Data ...............................................................................................................................................401

Troubleshooting

5.1 General....................................................................................................................................................501

5.2 General Failure Symptoms......................................................................................................................501

5.3 Failure Symptoms during Operation........................................................................................................502

5.4 Error Code Output ......................................................................................................................................503

Functional Tests

6.1 General....................................................................................................................................................601

6.2 Adjustments.............................................................................................................................................601

6.2.1 Adjustment of the CO₂Contents.................................................................................................601

6.3 Components Testing ...............................................................................................................................602

6.3.1 Glow Plug Resistance Test .........................................................................................................602

6.3.2 Flame Sensor Resistance Test...................................................................................................602

List of Contents

Air Top 2000 S

Circuit Diagrams

7.1 General....................................................................................................................................................701

Servicing

8.1 General....................................................................................................................................................801

8.2 Work on the Air Heater............................................................................................................................801

8.3 Work on the Vehicle ................................................................................................................................801

8.4 Air Heater Test Run.................................................................................................................................801

8.5 Servicing..................................................................................................................................................801

8.6 Visual Inspections and Installation Regulations ......................................................................................801

8.6.1 Heating Air System......................................................................................................................801

8.6.2 Fuel Supply .................................................................................................................................802

8.6.3 Dosing Pump...............................................................................................................................804

8.6.4 Fuel Filter ....................................................................................................................................804

8.6.5 Combustion Air Supply................................................................................................................805

8.6.6 Exhaust Line ...............................................................................................................................805

8.6.7 Combustion Air Intake and Exhaust Lines ..................................................................................805

8.6.8 Electrical Connections.................................................................................................................806

8.7 Removal and Installation .........................................................................................................................808

8.7.1 Air Heater, Removal and Installation...........................................................................................808

8.8 Start-Up...................................................................................................................................................808

Repair

9.1 General....................................................................................................................................................901

9.1.1 Work on Components after Disassembly....................................................................................901

9.1.2 Incorporation of Modifications .....................................................................................................901

9.2 Disassembly and Assembly.....................................................................................................................902

9.2.1 Removal of Housing Components/Covers..................................................................................902

9.2.2 Replacement of Control Unit.......................................................................................................903

9.2.3 Replacement of Temperature Limiter..........................................................................................903

9.2.4 Replacement of Combustion Air Fan ..........................................................................................905

9.2.5 Replacement of Flame Sensor....................................................................................................907

9.2.6 Replacement of Glow Plug..........................................................................................................907

9.2.7 Replacement of Burner Insert, Combustion Tube, and Heat Exchanger....................................910

10. Packaging/Storage and Shipping

10.1 General..................................................................................................................................................1001

Air Top 2000 S

List of Figures

501

502

General Failure Symptoms .............................................................................................................................501

Failure Symptoms during Operation ...............................................................................................................502

601

Adjustment of CO₂Contents ..........................................................................................................................601

701

702

703

704

Terminal Pin Assignment, Air Top 2000 S.......................................................................................................701

Circuit Diagram Automatic Control Air Top 2000 S, 12V/24V with Control D i a l ............................................702

Circuit Diagram Automatic Control Air Top 2000 S, 12V/24V with Combination Timer ..................................703

Circuit Diagram Automatic Control Air Top 2000 S,

12V/24V with Control Dial and Standard Timer ..............................................................................................704

705

Connection Diagram, Air Top 2000 S with Combination Timer.....................................................................705

801

802

803

804

805

806

807

808

809

810

811

812

813

Fuel Supply.....................................................................................................................................................802

Webasto Fuel Tank Tap .................................................................................................................................803

Fuel Tapping from Plastic Tank (tapping via fuel drain plug)..........................................................................803

Fuel Tapping from Plastic Tank (tapping via fitting plate)...............................................................................803

Pipe/Hose Connection....................................................................................................................................804

Dosing Pump, Installation Position and Attachment .......................................................................................804

Fuel Filter........................................................................................................................................................804

Exhaust Muffler, Direction of Flow..................................................................................................................805

Exhaust Pipe Outlet, Installation Position .......................................................................................................805

Weather Resistant Fuse Holder........................................................................................................................806

Control Dial...................................................................................................................................................806

Pulling the Plug...............................................................................................................................................806

Example of an Installation...............................................................................................................................807

901

902

903

904

905

906

Removal of Housing Components/Covers......................................................................................................902

Replacement of Control Unit and Temperature Limiter...................................................................................904

Replacement of Combustion Air Fan (Disassembly)......................................................................................905

Replacement of Combustion Air Fan (Assembly............................................................................................906

Disassembly of Heat Exchanger (Sheet 1 of 2)..........................................................................................908

Disassembly of Heat Exchanger (Sheet 2 of 2)..........................................................................................909

III

List of Figures

Air Top 2000 S

1. Introduction

1 Introduction

1.4 Safety Information and Regulations

The general safety regulations for the prevention of acci-

dents and the relevant operating safety instructions have

to be observed at all times."General Safety Regulations"

beyond the scope of these regulations are detailed in the

following.The specific safety regulations applicable to

this manual are highlighted in the individual chapters by

Warnings, Cautions, and Notes.

1.1 Scope and Purpose

This repair shop manual is intended to support famil-

iarized personnel in the repair of the Air Top 2000 S.

1.4.1 General Safety Notes

1.1.1 Use of Air Heaters

Within the scope of the StVZO (Road Licensing Regula-

tions of the Federal Republic of Germany) “Design

General Approvals”, laid down by the Federal Office for

Motor Traffic, exist for the Air Top 2000 S with the

following official marks of conformity:

The air heater Air Top 2000 S is used to

- heat the cabin

- defrost the windscreens.

They are not cleared for heating a transportation com-

partment for dangerous goods.

-S 324 (Diesel)

-S 325 (Gasoline)

The heaters operate independent from the vehicle en-

gine and are connected to the fuel tank and to the electri-

cal system of the vehicle. Their use is possible in

vehicles with water- or air-cooled engines.

The installation of the heater is to be performed in ac-

cordance with the installation instructions and must be

checked in case of

a) the vehicle type inspection in accordance with

§ 20 StVZO

b) the individual inspection in accordance with

§ 21 StVZO or

1.2 Meaning of Warnings, Cautions

and Notes

c) the examination in accordance with § 19 StVZO

performed by an officially authorised expert or exam-

iner for road traffic, a vehicle inspector or a public

servant as per section 7.4 a of Annex VIII to the

StVZO.

In the event of c) the installation must be certified on the

acceptance certificate included in the copy of the

“General Operating License” giving details about

WARNINGS, CAUTIONS, and NOTES in this manual

have the following meaning:

WARNING

This heading is used to highlight that non-compliance

with instructions or procedures may cause injuries or

lethal accidents to personnel.

manufacturer

type of vehicle , and

vehicle identification number.

CAUTION

This heading is used to highlight that non-compliance

with instructions or procedures may cause damage to

equipment.

This validates the “Design General Approval”.

The acceptance certificate must be kept with the

vehicle.

NOTE

The year of first operation must be permanently

marked on the identification label.

This heading is used to highlight and draw specific atten-

tion to information.

The heaters are cleared for heating the passenger and

driver cabins but not for heating compartments intended

for the transportation of dangerous goods.

1.3 Additional Documentation to be used

This workshop manual contains all information and pro-

cedures necessary for the repair of the Air Top 2000 S.

The use of additional documentation is normally not

necessary.

Operating instructions/installation instructions and the

vehicle specific installation proposal may be used as

complementary information as necessary.

101

1 Introduction

Air Top 2000 S

The heater must not be installed in the passenger or

driver compartments of busses. Should the heater never-

theless be installed in such a compartment, the installa-

tion box must be sealed tight against the vehicle interior.

There must be sufficient ventilation of the installation box

from the exterior in order not to exceed a maximum tem-

perature of 40 °C in the installation box.

Heating Air System

Heating air intake openings must be arranged so that

under normal operating conditions exhaust fumes of the

vehicle engine or air heater are not likely to be expected.

Extracting combustion air from the vehicle interior is not

permissible.

At filling stations and fuel depots the heater must be

switched off as there is a potential danger of explo-

sion.

Combustion Air Line

The combustion air required must be taken from the

exterior.

Within rooms accommodating persons, the combustion

air lines must not have more than four disconnects and a

splash-water protected exterior wall feedthrough. The

disconnects must be sealed in a way not to exceed a

leak rate of 200 l/h at an overpressure of 0.5 mbar.

The line including feedthrough, disconnects, material

and specific type must be described in the installation

instructions.

Where flammable fumes or dust may build up (e.g.

in the vicinity of fuel, coal, wood, cereal depots, or

similar installations) the heater must be switched off

to prevent explosions.

Due to the danger of poisoning and suffocation the

heater must not be operated in enclosed areas such as

garages or workshops without exhaust venting, not even

if the start-up is activated by the timer or telestart device.

The line must require tools for installation and removal,

must be protected against damage, and must be shock-

proof.

When removing the heater the gasket below must be re-

placed.

Exhaust Line

Heaters must be designed to discharge the exhaust to

The heat exchanger of the air heater remains service- the exterior.

able for a maximum of 10 years and must then be re-

placed with an original spare part by the manu-

facturer or by one of its authorized workshops.

The heater must then be provided with a label

Exhaust pipes must be routed so that exhaust fumes are

unlikely to penetrate into the vehicle’s interior.

The function of any parts of the vehicle essential for its

marked with the sales date and with the words “Orig- operation must not be impaired. Condensate or water

inal Spare”.

penetrated must not be able to accumulate in the

exhaust line.

Drain holes are permissible; these must drain the fluid to

the exterior via lines sealed against the vehicle interior.

Should exhaust pipes be routed through rooms

accommodating persons, these pipes shall also be

renewed after 10 years.

Installations not legally authorized will void the air

heater’s “Official Marks of Conformity” and thus the

vehicle’s permit of operation. The same applies for

repairs performed by unskilled personnel and repairs

with no original spare parts.

The exhaust line outlet is to be positioned to the top, to

the side, or in case of exhaust venting below the vehicle

floor, to the nearest possible location of the vehicle’s or

cockpit’s side or rear end. In compartments accommo-

dating persons, exhaust lines must not have more than

one disconnect and must have a splash-water protected

feedthrough in the exterior wall/floor. For water, that has

penetrated into the exhaust line, the connection of a

drain line with a metal-sealing joint is permissible. The

drain pipe must be routed sealed through the exterior

wall or the vehicle floor.The heat exchanger, the exhaust

line connected, as well as the possible drain pipe must

be sealed so that with an overpressure of double the

overpressure of the exhaust having the maximum per-

missible exhaust line length - at least however at an over-

pressure of 0.5 bar - a total leak rate of 30 l/h is not

exceeded.

1.5 Legal Provisions for Installation

For testing the heater in accordance with 19, 20, or 21

of the StVZO the following regulations are to be ob-

served in particular (§ 22 a StVZO):

Testing is performed upon presentation of the operating

and installation instructions of the manufacturer.

The year of the initial operation must be durably marked

on the heater identification plate by the installing person.

The line including feedthrough, disconnects, material

and specific type must be described in the installation

instructions.

The line must require tools for installation and removal,

must be protected against damage, and must be shock-

proof.

102

Air Top 2000 S

1 Introduction

Metal lines must be used. These may not heat to more

than 110 °C should there be the possibility of contact

within the room interior. Protective devices against con-

tact may be fitted.

Should exhaust pipes be routed through rooms accom-

modating persons, these pipes shall be renewed after 10

years using genuine spare parts.

Combustion Air Inlet and Exhaust Outlet

During installations these ports for combustion air entry

and exhaust fume exit must be of such type, that a ball

with a diameter of 16 mm cannot be inserted. Electrical

lines, switch gear and control gear of the heater must be

located in the vehicle so that their proper function cannot

be impaired under normal operating conditions.

For the routing of fuel lines and the installation of addi-

tional fuel tanks §§ 45 and 46 of the StVZO are to be

adhered to.

The most important regulations are: Fuel lines are to be

designed in such a way that they remain unaffected by

torsional stresses in the vehicle, engine movement and

the like. They must be protected against mechanical

damage.

Fuel-carrying parts are to be protected against ex-

cessive heat and are to be arranged so that any dripping

or evaporating fuel can neither accumulate nor be ig-

nited by hot components or electrical equipment.

In busses, fuel lines and fuel tanks may be located

neither in the passenger area nor in the driver’s compart-

ment. In these type of vehicles the fuel tanks must be lo-

cated such that they do not pose a direct hazard to the

exits in the event of a fire. Fuel supply must not be by

means of gravity or pressurization of the fuel tank.

Installation Rules for Webasto Fuel Tanks for the

Fuel Supply of Heaters in Vehicles

In busses the installation is not permitted in the pas-

senger or driver compartment.

The fuel fill neck must in no vehicle be located within any

of these compartments.

Fuel containers for gasoline fuel must not be located

immediately behind the front panelling of the vehicle.

They must be sparate from the engine so that even in

case of an accident the inflammation of fuel is unlikely to

be expected. This does not apply for towing vehicles

with an open cockpit.

The operational state of the heater, i.e. an indication “on”

or “off”, must be easily and clearly visible.

103

2 General Description

2. General Description

Air Top 2000 S

A malfunction of the Air Top 2000 S is indicated by an

error code displayed on the combination or standard

timer. When equipped with the standard control dial,

the operating indicator flashes. In addition a heater check

out may be performed using a personal computer (refer

to operating instructions PC air heater diagnosis).

The air heater Air Top 2000 S operates under the

evaporator principle and basically consists of:

- combustion and heating air fan

- heat exchanger

- burner insert with combustion tube

- control unit

Air Heater Air Top 2000 S

(covers removed)

Air Heater Air Top 2000 S

2.1 Combustion and Heating Air Fan

The combustion and heating air fan delivers the air re-

quired for combustion from the combustion air inlet to

the burner insert. By means of the fan the heating air is

also delivered to the hot air outlet.

For control and monitoring a

- control unit/control circuit board

- flame sensor

- glow plug

- temperature limiter

- temperature sensor

are located within the unit.

All Air Top 2000 S heaters may be controlled

by means of an optional external temperature sensor.

Fuel supply is provided externally by a fuel dosing pump.

Combustion and Heating Air Fan

201

Air Top 2000 S

2 General Description

2.2 Heat Exchanger

2.4 Control Unit / Control Circuit Board

The heat exchanger dissipates the heat provided by

combustion to the air delivered by the combustion and

heating air fan.

The control unit/control circuit board is the central con-

trolling unit for functional sequencing and monitoring of

the combustion operation. A temperature sensor located

on the control unit is used for temperature control. All

heaters may have the temperature sensor replaced

with an external temperature sensor. The combustion

and heating air fan may be set by means of a poten-

tiometer.

A malfunction in the Air Top 2000 S is indicated by an

error code displayed on the combination or standard

timer. When equipped with a standard control dial

the operating indicator flashes. In addition a heater check

out may be performed using a personal computer (refer

to operating instructions PC air heater diagnosis).

Heat Exchanger

Potentiometer

2.3 Burner Insert with Combustion Tube

Within the burner insert fuel is distributed in the combus-

tion tube across the burner cross-section. In the combus-

tion tube the combustion of the fuel/air mixture takes

place heating up the heat exchanger.

Temperature

Sensor

Combustion

Tube

Control Unit - Air Top 2000 S

Burner

Insert

Fuel

1 mm

Diesel

2 mm

202

2 General Description

Air Top 2000 S

2.5 Flame Sensor

2.7 Temperature Limiter

The flame sensor is a low-Ohm PTC resistor changing

its resistance dependent on its heating by the flame.

The signals are routed to the control unit for processing.

The flame sensor monitors the flame operating condition

over the complete duration of heater operation.

The temperature limiter protects the air heater against

excessive operating temperatures. Overheat protection

is activated at a temperature higher than 150 °C to inter-

rupt the electrical circuit of the dosing pump and switch

off the heater with run-down operation.

After cooling down the electrical circuit is restored.

The air heater may be switched on again (see 3.1.8).

Flame Sensor

Temperature Limiter

2.6 Glow Plug

The glow plug ignites the fuel/air mixture at the start of

the air heater operation. The glow plug is acting as an

electrical resistor and is located in the burner insert

opposed to the flame side.

2.8 Dosing Pump

The dosing pump is a combined supply, dosing and shut-

off system for the fuel supply of the heater out of the

vehicle’s fuel tank.

Glow Plug

Dosing Pump DP 2 for Gasoline and Diesel

operated Heaters

Dosing Pump DP 30 for Diesel operated Heaters

203

Air Top 2000 S

3 Functional Description

Functional Description

Should no proper combustion develop within 120 sec-

onds (for fuel-operated within 115 seconds) the combus-

tion and heating air fan speed is increased to full load for

approx. 30 seconds (15 seconds for fuel-operated

heaters) with the glow plug on and the dosing pump off

(no fuel delivery) with a subsequent automatic restart.

3.1 Functional Description Air Top 2000 S

3.1.1 Control Element

The control element is used to switch the air heater on

and off, set the desired room temperature (air intake tem-

perature between 10 °C and 45 °C), and to unlock a

failure interrupt condition.

Should the no-combustion-condition persist, after an-

other 80 seconds (for fuel operated heaters after approx.

85 seconds) there will be a switch-off by error lockout

(see 3.1.8) with a run-down of the combustion and heat-

ing air fan lasting 120 seconds at 2/3 of its max. speed.

The green LED indication is used to indicate the opera-

ting condition (LED permanently on) and an overheat

condition (LED flashes).

2. Start (automatic restart)

Fan speed is again reduced to approx. 30% (for fuel

operated heaters to approx. 50%) and fuel is delivered.

During the next 20 seconds fan speed is increased to ap-

prox. 60% (for fuel-operated heaters to approx. 75%) of

full speed. As soon as a flame is detected within the next

55 seconds, combustion will be stabilized. Should there

be no flame condition after a total fuel delivery period of

180 seconds, fuel delivery will be stopped and the glow

plug deactivated. The combustion air fan continues full

load operation for another 120 seconds (run-down) and

the heater enters the error lockout condition.

3.1.2 Switch-On

The control element is set to the desired room tempera-

ture. When switching the air heater on, the operating indi-

cator is illuminated and the glow plug is activated

(cycled). The motor of the combustion and heating air

fan starts high-speed operation for 1 second (break-

away moment) and is then under slow-down control to

approx. 30% (Diesel) or 50% (fuel) of full speed.

NOTE

Should the temperature of the intake air be above the se-

lected, rated temperature, only the motor of the combus-

tion and heating air fan will operate (control idle). Start

operation will be initiated with a heating air temperature

below the rated temperature.

3.1.3 Stabilization

Diesel Operated Heaters

With the glow plug activated the operating speed of the

combustion and heating air fan is increased. After an-

other 20 seconds the speed of the combustion and heat-

ing air fan is continuously increased within 17 seconds

to full load for full heat.

The flame sensor function is checked. If the flame sen-

sor at this time already signals “flame”, there will be a

120 second run-down and an error lockout of the control

unit. A malfunction of any other component monitored

causes an error lockout without run-down.

NOTE

This operating condition is omitted if the set temperature

(control idle) has already been achieved once.

The glow plug is deactivated and heating operation com-

mences. A flame-out during speed up control causes a

restart, 5 restarts an error lockout of the heater.

After approx. 20 seconds (for fuel operated heaters after

approx. 15 seconds) the fuel dosing pump is activated.

After another 25 seconds the speed of the combustion

and heating air fan is continuously increased to a higher

rate and combustion begins. As soon as a flame is

detected, combustion will be stabilized (see 3.1.3).

Fuel Operated Heaters

With the glow plug activated the operating speed of the

combustion and heating air fan is continuously increased

within 4 seconds to full load for full heat. This operating

condition will be omitted if the start occurs after a control

idle period.

The glow plug is deactivated and heating operation com-

mences. A flame-out during speed up control causes a

restart, 5 restarts an error lockout of the heater.

Should no normal combustion be achieved within 120

seconds (for fuel operated heaters after approx. 115

seconds), the speed of the combustion and heating air

fan is increased for approx. 30 sec and there will be an

automatic repeat start with the glow plug activated and

fuel dosing pump deactivated (no fuel supply).

301

3 Functional Description

Air Top 2000 S

3.1.4 Heating Operation

3.1.7 Switch-Off

During operation the combustion exhaust gasses flow

through the heat exchanger charging its walls with com-

bustion heat, which in turn is taken up by the heating air

delivered by the heating air fan to be routed to the ve-

hicle interior.

Switching the heater off extinguishes the operation indi-

cation of the control element.

If no fuel has been delivered or if the air heater is in con-

trol idle, the air heater is deactivated immediately

without run-down.

The temperature of the heating air sucked in is

measured by means of a temperature sensor fitted to

the air intake side of the air heater or by means of an ex-

ternally located temperature sensor.

A temperature below the one set with the control ele-

ment increases the heater performance up to maximum

heat. In order to extend the burner idle period of Diesel

operated heaters during permanent operation with a

heating performance in excess of 1.1 kW, the fuel dos-

ing pump delivery rate is reduced every 15 minutes for

20 seconds.

If fuel supply has commenced it will be immediately

stopped at switch-off. Fan speed remains constant and

then decreases within 30 seconds to approx. 60% of full

speed. After this or with the flame sensor detecting “no

flame”, fan speed rises to maximum speed for 60 sec-

onds and run down for 120 seconds is initiated. Run-

down is at approx. 60% of full speed and is deactivated

automatically.

NOTE

Re-activation of the heater during run-down is permitted.

Run-down will be completed first with a subsequent re-

start.

A heating performance less than 1.1 kW causes the fuel

delivery to the dosing pump to be interrupted every 30

minutes for 4 seconds. Additionaly heating operation is

briefly suspended every 9 hours like in control idle. For

Diesel-operated heaters this is only applicable, if at this

time heating performance is less than 1.1 kW.

3.1.8 Switch-off upon Failure

The control unit recognizes failures of individual air

heater components and malfunctions in the start se-

quence and in normal operation.

3.1.5 Control Operation

During control operation fan speed and dosing pump

rate of delivery are subject to heating performance.

The glow plug is deactivated.

The air heater is deactivated and enters the error lock

out mode under the following conditions:

flame sensor open or short circuit

temperature sensor open or short circuit

glow plug open or short circuit

fan motor open or short circuit or fan speed wrong

dosing pump open or short circuit

3.1.6 Control Idle

After reaching the temperature set with the control ele-

ment, heating performance is controlled to decrease.

The speed of the combustion and heating air fan slows

down and the fuel delivery rate to the dosing pump is re-

duced. When exceeding the air intake temperature set

with the control element during minimum heating perfor-

mance, the dosing pump is deactivated after 5 seconds

and combustion terminates.

Fan speed remains constant for 35 seconds and is then

increased to approx. 60% of full speed for cooling the

heater down. the fan then continues to operate at ap-

prox. 30% of full speed until temperature is below the

temperature set with the control element. If temperature

falls below the one set with the control element, the

heater will restart (without break away).

overheating

low voltage below 10 Volt or high voltage above

15 Volt in excess of 20 seconds for 12 Volt heaters

low voltage below 20 Volt or high voltage above

30 Volt in excess of 20 seconds for 24 Volt heaters

A switch-off like in “switch-off” will be performed.

In case of overheating there will be no fuel supply. After

run-down the control unit is in the error lockout mode.

The operation indication outputs a flash code.

For error unlock the air heater has to be switched off

momentarily (at least 2 seconds) before switching on.

NOTE

New settings on the control element are executed by the

control unit/heater with a time delay.

302

Air Top 2000 S

4 Technical Data

Fuel for Air Top 2000 S B (gasoline):

Technical Data

The fuel specified by the manufacturer must be used.

As long as no threshold values are given, the following

technical data are understood to include tolerances of

10% usual for heaters at an ambient temperature of

+20 °C and at nominal voltage and conditions.

Fuel for Air Top 2000 S D (diesel/PME):

The diesel fuel specified by the vehicle manufacturer

must be used.

We know of no negative influences due to additives.

Electrical Components:

If fuel is extracted from the vehicle’s tank, follow the

additive instructions issued by the vehicle manufacturer.

Control unit, combustion air fan, dosing pump, timer,

glow plug and control dial are for 12 or 24 Volts

operation.

If you change to low-temperature fuel, the heater must

be operated for approx. 15 minutes so that the fuel

system is filled with the new fuel.

The components temperature limiter and flame detector

are independent of voltage.

The Air Top 2000 S D heater is also licensed for use with

PME (bio-diesel), which complies with ASTM D6751 and

DIN EN 14214.

Air Heater

Operation

AT 2000 S B

~ S 325

AT 2000 S D

~ S 324

Mark of conformity

Heater type

Air heater with evaporator burner

Heat flow

Control range

1.1 – 2.0 kW

Gasoline

0.9 – 2.0 kW

Diesel/Fuel oil (EL)

Type of fuel

0.1 .. 0.2 kg/h (0.16..0.27 l/h)

12 Volt

0.1 .. 0.21 kg/h (0.12 .. 0.24 l/h)

Fuel consumption

Nominal voltage

Operation voltage

12 Volt

24 Volt

10 … 15 Volt

20 … 30 Volt

Rated power consumption Control range

Permitted ambient temp.:

9 ...22 W

-40 ° … +40 °C

-40 ° … +85 °C

-40 ° … +20 °C

-40 ° … +85 °C

-40 ° … +75 °C

-40 ° … +85 °C

- operation

- storage

Heater:

- operation

- storage

Dosing pump:

Control element:

- operation

- storage

Permitted combustion air

intake temperature

-40 ... +20 °C

Setting range for

+10 ... +45 °C

Control range

Max.

indoor temperature

Volume flow of heating air

against 0.5 bar

70 m /h

CO₂in exhaust

(perm. functional range)

9.5 … 10.5

9.5 … 12.0

Max.

Dimensions air heater

Weight, heater

Length 311 2 mm

Width 120 1 mm

Height 121 1 mm

2.6 kg

401

5 Troubleshooting

5. Troubleshooting

Air Top 2000 S

CAUTION

Troubleshooting is normally limited to the isolation of

defective components.

The following causes for trouble are not considered and

should always be checked for to exclude them as cause

for trouble:

5.1 General

A malfunction of the Air Top 2000 S is indicated by an

error code displayed on the combination or standard

timer. When equipped with a standard control dial

the operating indicator flashes. In addition a heater check

out may be performed using a personal computer (refer

to operating instructions PC air heater diagnosis).

corrosion on connector

loose contact on connector

wrong crimping on connector

corrosion on electrical wiring and fuses

corrosion on battery terminals

If individual components are checked, the control unit

electrical connections must be disconnected.

CAUTION

Troubleshooting requires profound knowledge about

structure and theory of operation of heater components

and may only be performed by skilled personnel.

After any correction of a failure a functional test has to

be performed in the vehicle.

In cases of doubt refer to Sections 2 or 3 for functional

interrelations.

5.2 General Failure Symptoms

The following table (Fig. 501) lists the possible failure

symptoms.

Failure Symptom

Probable Cause

Remedy

Air heater switches

off automatically

No combustion after start or repeat

start

Switch off heater momentarily and

switch on once again

Flame extinguishes during

operation

Switch off heater momentarily and

switch on once again

Heater overheats

Check heat air ducting for

Operation indication flashes

obstructions, allow heater to cool

down, switch off heater momentarily

and switch on once again

Vehicle electrical

Charge battery

system voltage too low

Switch off heater momentarily and

switch on once again

Heater expels black fumes

Combustion air and/or

exhaust ducting blocked

Check combustion and exhaust

ducting for obstructions

Fig. 501 General Failure Symptoms

501

Air Top 2000 S

5 Troubleshooting

failure symptom listed, in emergencies, assistance by our

service technicians may be requested.

5.3 Failure Symptoms during Operation

The following table (Fig. 502) lists the possible failure

symptoms as they might occur during the functional

sequence of operation.

NOTE

Overheating and dosing pump failure are always indi-

cated additionally after run-down by the flashing LED of

the control dial.

In case of malfunction the failure is to be isolated and

removed using this table. It is important to accurately

identify the failure symptom.

In all cases of trouble also a defective control unit may

be the cause should all other components turn out to be

serviceable.

Should the failure symptom not be contained in this

table or the trouble not be detected under the specific

Possible Causes

Failure Symptom

shows after

....seconds

Wrong cabling, defective fuse

Fan or control unit defective or fan blocked

No start and no illumination

of LED on control element

immediately

No start but LED illuminates

Very low speed with no start

immediately

Control idle operation: wrong manual control (selected

temperature is below air intake temperature) or wrong

integration (excessive air intake temperature)

Glow plug or flame sensor short or open circuit or

control unit defective

Motor operates momentarily

and then stops

Fan motor obstructed, binding

Flame detection erroneous

Voltage to control unit too low

Stoppage without run-down

Run-down after

120

Cabling to dosing pump, pump itself or overheat

protection defective

Run-down after

and dosing pump does not cycle

Intermittent disconnect of connection to dosing pump

or to overheat protection

Run-down after

40 to 120

230

No flame: wrong fuel supply quantity, defective or slow

fan, coked burner (in particular pilot flame outlet bore),

combustion air/exhaust ducting obstructed or heat

exchanger coked, dosing pump seized

Overheating or

voltage too low or

Run-down

during combustion

operation

component error (flame sensor, glow plug,

overheat sensor, dosing pump, burner) or

no fuel supply or obstructed combustion air/exhaust

ducting

Fan motor failure or seizure

Stoppage without run-down

during combustion

operation

Flame-out by gas bubbles in fuel delivery or strong

wind against exhaust outlet or defective no-flame

detection

Interruption of dosing pump

cycling and max. speed for

30 sec with subsequent re-start

during combustion

operation

Fig. 502 Failure Symptoms during Operation

502

5 Troubleshooting

Air Top 2000 S

5.4 Error Code Output

When equipped with a combination or standard timer a

malfunction will cause an error code output to the dis-

play of the timer for indication.

NOTE

When equipped with a control dial, the error code

output is indicated by flashing of the operating indica-

tor/error code indication. The number of flash pulses

corresponds to the number indicated in the table below.

After a quick pulse train there will always be an error

code output.

Error code output on display of combination or

standard timer

No start (after 2 attempts)

Flame out (at least >5)

Voltage too low or too high

Premature flame detection

Flame sensor open or short circuit

Temperature sensor open or short circuit

Dosing pump open or short circuit

Fan motor open or short circuit or

wrong speed

Glow plug open or short circuit

Overheating

503

Air Top 2000 S

6 Functional Tests

CAUTION

Functional Tests

Set potentiometer slowly; observe end positions.

Adjustment may be performed at any electrical system

voltage.

6.1 General

This section describes the on-vehicle and off-vehicle

testing of the air heater to check its proper operation.

Clockwise rotation increases the fan speed and de-

creases the CO₂contents. Counterclockwise rotation de-

creases the fan speed and increases the CO₂contents.

WARNING

The air heater shall not be operated in enclosed areas

like garages or workshops not provided with exhaust

venting facilities.

If the setting range is not sufficient (e.g. after replace-

ment of the combustion and heating air fan) the manufac-

turer’s setting may be cancelled according to the

procedure described in the following.

6.2 Adjustments

6.2.1.2 New Basic Setting

6.2.1 Adjustment of the CO Contents

CAUTION

The manufacturer’s setting cannot be restored.

6.2.1.1 General

1. Withdraw cover from upper shell according to 9.2.1.

2. Switch on air heater.

3. Rotate potentiometer two times and with no interrupt

through its complete setting range (e.g. max. - min.-

max.).

4. Adjust desired CO₂contents (Fig. 601).

5. Switch off air heater.

6. Install cover and secure.

The CO₂contents of the exhaust is adjusted with the

potentiometer on the control circuit board. The air heater

is preset by the manufacturer with respect to the com-

bustion and heating air fan fitted. After adjustment by the

manufacturer the potentiometer is in center position

(Fig. 601). After an inadvertent loss of this position it is

sufficient to restore its original position.

The manufacturer setting may be corrected by rotating

the potentiometer. A suitable tool like a small screw

driver (2.5 mm tip) is to be used.

CO₂

–

Fig. 601 Adjustment of CO₂Contents

601

6 Functional Tests

Air Top 2000 S

6.3 Components Testing

CAUTION

During electrical testing always ensure that the control

unit and the component under test are electrically discon-

nected from each other.

6.3.1 Glow Plug Resistance Test

During electrical testing of the glow plug using a digital

multimeter, the following readings should be obtained:

Glow plug

Resistance at 25 °C: 0.324 ... 0.360 Ω 1.3 ... 1.44 Ω

Test current: < 5 mA < 5 mA

12 Volt (red)

24 Volt (green)

6.3.2 Flame Sensor Resistance Test

During electrical testing of the flame sensor using a digi-

tal multimeter, the following readings should be obtained:

Cold test:

Resistance at 25 °C:

Test current:

2.6 ... 3.4 Ω

< 5 mA

Hot test:

Resistance at 800 - 1000 °C:

12 ... 15 Ω

(ceramic rod red hot over a length of approx. 20 mm)

Test current: < 5 mA

602

Air Top 2000 S

7 Circuit Diagrams

Circuit Diagrams

7.1 General

The air heater Air Top 2000 S may be operated

using the control dial (rated value transmitter/switch)

or with the control dial and a combination or

standard timer. The circuit diagrams (Figs. 702 to 704)

show the possible circuits 12 or 24 Volt with

control element

combination timer

control element and standard timer

Fig. 701 shows the terminal pin assignment.

violet

black

brown

yellow

blue

= Connection, Combustion and Heating Air Fan

= Connection, Dosing Pump

= Connection, Flame Sensor

= Connection, Glow Plug

= Connection, Temperature Limiter

Fig. 701 Terminal Pin Assignment, Air Top 2000 S

701

7 Circuit Diagrams

Air Top 2000 S

Item

Nomenclature

Air Heater

Remark

Wire Gauges

Air Top 2000 S

< 7.5 m

7.5 - 15 m

Control Unit

1.5 mm

0.75 mm

Flame Sensor

1.0 mm

1.5 mm

2.5 mm

1.5 mm

2.5 mm

Temperature Sensor

Temperature Limiter

Glow Plug

4.0 mm

6.0 mm

Wire Colours

Fuse 24V 10A/12V 15A

LED green (in item S1)

Motor

Flat Fuse SAE J 1284

Operation indication

blue

brown

yellow

green

grey

orange

red

black

violet

white

Control Element

Connection 2-pole

Connection 8-pole

Connection 4-pole

Connection 2-pole

Connection 6-pole

Connection 1-pole

Dosing Pump

Rated Value Setting Switch

of item A2

X1-X5

of item A2

of item S

of item A2

Connection X11/2 and X11/3

for TRS function only

X11

X12

of item A2

Diagnosis (K-wire)

Fig. 702 Circuit Diagram Automatic Control Air Top 2000 S, 12V/24V with Control Dial

702

Air Top 2000 S

7 Circuit Diagrams

Item

Nomenclature

Air Heater

Remark

Wire Gauges

Air Top 2000 S

< 7.5 m

7.5 - 15 m

Control Unit

1.5 mm

0.75 mm

Flame Sensor

1.0 mm

1.5 mm

2.5 mm

1.5 mm

2.5 mm

Temperature Sensor

Temperature Limiter

Glow Plug

4.0 mm

6.0 mm

Wire Colours

Fuse 24V 10A/12V 15A

LED red (in item P)

Flat Fuse SAE J 1284

blue

Instant heat switch illumination,

standy indication,

operating indicator light

brown

yellow

green

grey

orange

red

Heating symbol in display (in item P)

Operating indicator light,

overheat indication

black

violet

white

Light (in item P)

Motor

Symbol illumination

Combination Timer (1531)

Switch

Instant heating remote control

of item A2

with plus from terminal (15/75)

to connection 10:

permanent operation during

instant heating as long as

ignition on

X1-X5

Connection 2-pole

Connection 8-pole

Connection 2-pole

Connection 6-pole

Connection 1-pole

Connection 12-pole

Dosing Pump

of item A2

without plus to connection 10:

heating time programmable as

required (10 min to 120 min),

default setting 120 min.

X11

X12

X13

of item A2

Diagnosis (K-wire)

of item P

Connection X11/2 and X11/3

for TRS function only

Fig. 703 Circuit Diagram Automatic Control Air Top 2000 S, 12V/24V with Combination Timer

703

7 Circuit Diagrams

Air Top 2000 S

Item

Nomenclature

Air Heater

Remark

Wire Gauges

Air Top 2000 S

Control Unit

< 7.5 m

7.5 - 15 m

1.5 mm

0.75 mm

Flame Sensor

1.0 mm

1.5 mm

2.5 mm

1.5 mm

Temperature Sensor

Temperature Limiter

Glow Plug

2.5 mm

4.0 mm

6.0 mm

Fuse 24V 10A/12V 15A

LED red (in item P)

Flat Fuse SAE J 1284

Wire Colours

Instant heat switch illumination,

standy indication,

operating indicator light

blue

brown

yellow

green

grey

orange

red

Heating symbol in display (in item P)

Operating indicator light,

overheat indication

Light (in item P)

Motor

Symbol illumination

black

violet

white

Standard timer

Control Element

Switch

Rated Value Setting Switch

Instant heating remote control

of item A2

with plus from terminal (15/75)

to connection 10:

permanent operation during

instant heating as long as

ignition on

X1-X5

Connection 2-pole

Connection 8-pole

Connection 4-pole

Connection 2-pole

Connection 6-pole

Connection 1-pole

Connection 12-pole

Dosing Pump

of item A2

of item S1

without plus to connection 10:

heating time programmable as

required (10 min to 120 min),

default setting 120 min.

X11

X12

X13

of item A2

Diagnosis (K-wire)

of item P

Connection X11/2 and X11/3

for TRS function only

Fig. 704 Circuit Diagram Automatic Control Air Top 2000 S,

12V/24V with Control Dial and Standard Timer

704

Air Top 2000 S

7 Circuit Diagrams

Combination Timer 1531

Black

Battery Positive

or Ignition Signal (10)

Grey

Lights (1)

(optional)

Red

Battery Positive (11)

1V2

2V4

Brown

Battery Negative (12, 4)

Adapter Harness

P/N 9008440A

12 11 10

Fig. 705 Connection Diagram, Air Top 2000 S with Combination Timer

705

7 Circuit Diagrams

Air Top 2000 S

706

Air Top 2000 S

8. Servicing

8 Servicing

For reasons of the air heater’s functional reliability per-

form the following servicing:

check heating air inlet and outlet for foreign matter

and contamination. (Contaminated or clogged heat-

ing air ducts may lead to overheating and thus

response of the temperature limiter).

Clean air heater exterior (prevent the ingress of

water).

8.1 General

This section describes the servicing procedures that

may be performed with the air heater installed.

8.2 Work on the Air Heater

Examine electrical connections for corrosion of con-

tacts and for security.

Check combustion air and exhaust ducts for damage

and obstructions.

Check fuel lines and fuel filter for leakage.

Replace fuel filter if installed.

Prior to performing any work it is mandatory to discon-

nect the vehicle battery main lead. As long as the air

heater is in operation or in run-down, the battery main

supply must not be disconnected due to the danger of

overheating resulting in a response of the overheat pro-

tection.

8.6 Visual Inspections and Installation

Regulations

When performing extensive repairs on the heater a com-

plete removal is advisable. When performing repairs re-

quiring a relocation of the installation position, the

relevant installation instructions and the vehicle-specific

installation proposal have to be observed.

8.6.1 Heating Air System

CAUTION

The integration of the air heater into the vehicle’s own air

system is not permitted due to the system’s high press-

ure and temperature.

8.3 Work on the Vehicle

CAUTION

Fitted in the air heater on the heating air intake side is a

temperature sensor, which operates the heater in the

relevant range of performance in conjunction with the

control dial dependent on the air intake temperature

and position of the rated value transmitter. Heating per-

formance is selected so that after quickly reaching the

preselected indoor temperature it is maintained at this

value. Air Top 2000 S heaters may be operated with an

external temperature sensor (see 9.1.2).

In the vicinity of the air heater a temperature of 85 °C

must not be exceeded under any circumstances (e.g.

during body paint work).

8.4 Air Heater Test Run

WARNING

The air heater must not be operated, not even with

timer, in enclosed areas like garages or workshops not

equipped with an exhaust venting facility.

Minimum inside diameter of the heating air duct is

55 mm. Standard diameter is 60 mm.

CAUTION

NOTE

Operation of the heater without the control unit cover is

not permitted and causes overheating.

For heating air ducting only materials may be used

which are temperature-proof to at least 130 °C.

8.5 Servicing

Maximum loss of pressure between suction and delivery

side of the heating air duct 1.0 mbar (10 mm water

column).

NOTE

In order to avoid the seizure of mechanical components,

the air heater should be operated every 4 weeks for at

least 20 minutes.

When exceeding this value the temperature limiter is

very likely to respond. The heating air hose is to be se-

cured at its joints.

The air heater does not require maintenance. It should

however be checked by Webasto-trained skilled person-

nel on regular intervals, the latest before the heating

season begins (point of time, when the heater is more

frequently in use due to weather conditions).

801

8 Servicing

Air Top 2000 S

8.6.2 Fuel Supply

The fuel is taken from the vehicle fuel tank or from a

separate fuel tank. The values for maximum pressure

at the fuel extraction point are shown in Fig. 801.

Permissible fuel inflow

height H

At maximum pressure in

fuel line

0.00 m (0.00 in.)

1.00 m (39.4 in.)

2.00 m (78.7 in.)

0.20 bar (2.9 PSI)

0.11 bar (1.6 PSI)

0.03 bar (0.44 PSI)

max. 3m (9.8 ft.)

Maximum fuel intake

height S

At maximum negative

pressure in fuel tank

iØ2mm

0.00 m (0.00 in.)

0.50 m (19.7 in.)

1.00 m (39.4 in.)

-0.10 bar (-1.45 PSI)

-0.06 bar (-0.87 PSI)

-0.02 bar (-0.29 PSI)

iØ2mm

8.6.2.1 Fuel Tapping

Vehicles with a Diesel Engine

The fuel must be taken from the vehicle fuel tank or

from a separate tank (Figs. 802, 803 and 804). This

separate fuel pickup precludes any effect of pressure.

≤ 10 m (32.8 ft.)

≤ 1.2 m (3.9 ft.)

≤ 8.8 m (28.8 ft.)

Vehicles with an Injection Engine

When installing the heater in a vehicle with fuel injection

systems, it is important to establish whether the fuel

pump is located inside or outside the tank.

Fig. 801 Fuel Supply

If the fuel pump is located inside the tank, fuel can only

be extracted from the return line using a Webasto fuel

tee fitting in which case it must be ensured that the

return line continues almost to the bottom of the tank.

If this is not the case, a Webasto fuel standpipe

(see Figs. 802, 803 and 804) may be used.

If the fuel pump is installed outside the tank, the fuel

connection may also be made between the tank and

fuel pump, again using only the Webasto fuel tee fitting.

Vehicles with a Carburetor Engine

The fuel may only be extracted on cars using a special

Webasto fuel tee fitting as close to the tank as possible.

The connection may be made in either the supply or

return line, in which case the return line must lead

almost to the base of the tank. If this is not the case,

the return line may be extended.

The fuel tee must be fitted in such a way that any air or

gas bubbles are automatically discharged towards the

tank.

The fuel tee should not be located near the engine, as

gas bubbles may form in the lines on account of heat

radiated from the engine. This may cause problems

during combustion.

802

Air Top 2000 S

8 Servicing

Hole Pattern

Fuel Tank Tap

Gaskets

25 mm (1 in.)

Tank Fitting Plate

Fig. 802 Webasto Fuel Tank Tap

* Use fuel tank tap only on metal fuel tanks

Fig. 804 Fuel Tapping from Plastic Tank

(tapping via fitting plate)

NOTE

Plastic Tank

The fitting plate must be made of sheet metal!

8.6.2.2 Fuel Lines

Fuel lines may only be steel, copper, or plastic lines

made of unhardened, light and temperature stabilised

PA 11 or PA 12 ( e.g. Mecanyl RWTL) according to DIN

73378. As in most cases a permanently rising fuel line

routing cannot be ensured, the inner diameter must not

exceed a certain value. Starting from an inside diameter

of 4 mm, air or gas bubbles accumulate resulting in mal-

functions should the lines be descending or have sags.

The diameters specified in Fig. 801 will ensure that

bubbles do not form.

Gasket

A descending line routing from the dosing pump to the

heater should be avoided.

Loose fuel lines must be secured in order to avoid sagg-

ing. The installation must ensure protection against

stone impacts and undue temperatures (exhaust line).

The fuel line joints are to be secured against slipping

with hose clamps.

Fig. 803 Fuel Tapping from Plastic Tank

(tapping via fuel drain plug)

803

8 Servicing

Air Top 2000 S

Connection of 2 Pipes with Hose

8.6.3.1 Installation Location

The proper connection of fuel lines with hoses is shown

in Fig. 805.

It is advantageous to mount the dosing pump in a cool

location. The ambient temperature must never exceed

+20 °C during operation.

Correct

Dosing pump and fuel lines must not be installed in loca-

tions exposed to heat radiated by hot vehicle compo-

nents. A heat shield is to be provided as required.

Clamp

8.6.3.2 Installation and Attachment

The dosing pump is to be attached with anti-vibration

mounts. The installation location is limited according to

Fig. 806 to ensure sufficient self-venting capability. Due

to the danger of corrosion the plug connection between

dosing pump and dosing pump cable loom may only use

Webasto original parts.

Wrong

Bubble

8.6.4 Fuel Filter

Fig. 805 Pipe/Hose Connection

Only a Webasto filter, P/N 50487171A, is allowed to be

used if the fuel is expected to be contaminated. Install

vertically if possible, however at most horizontally (check

flow direction).

8.6.3 Dosing Pump

The dosing pump is a combined delivery, dosing, and

shut-off system and is subject to certain installation crite-

ria (see Figs. 801 and 806).

0 - 90°

ø 5

Fig. 807 Fuel Filter

AT 2000 S. 12 Volt and 24 Volt - Gasoline and Diesel

0-90°

0°

AT 2000 S D. 12 Volt and 24 Volt - Diesel DP 30

Installation Position only Horizontal

Fig. 806 Dosing Pump, Installation Position

and Attachment

804

Air Top 2000 S

8 Servicing

Both lines must be routed away from the heater in a de-

scending attitude. If this is not possible, a condensate

drain hole ø 4 mm must be provided at the lowest point.

8.6.5 Combustion Air Supply

Combustion air must under no circumstances be ex-

tracted from rooms with persons. The combustion air

inlet must not point towards the forward direction of mo-

tion. It must be located so that no clogging by contamina-

tion is to be expected.

Inner diameter of lines:

Combustion air line: 22 mm

Exhaust line:

22 mm

NOTE

When exceeding an exhaust line length of 2 m, insulated

exhaust lines have to be used (below minimum dew

point).

For fuel operated heaters the combustion air tap must

be located in a possibly cool and splash water proof posi-

tion using a combustion air line.

Smallest bending radius: 50 mm

If the air heater is located in a closed installation box,

combustion air must be taken in from and the exhaust

routed to the exterior. The feedthroughs must not allow

exhaust fumes to enter the vehicle interior.

In order to ensure the angle of 90° 10°, an attachment

is required not further than 150 mm away measured

from the exhaust pipe end.

If a contamniated combustion air supply is expected, a

combustion air filter (Ident No. 21963A) can be fitted

(Air Top 2000 S D only).

8.6.6 Exhaust Line

Rigid pipes made of unalloyed or alloyed steel with a

minimum wall thickness of 1.0 mm have to be used as

exhaust line or flexible pipes made of alloyed steel only.

The exhaust pipe is secured to the air heater e.g. with a

clamp.

Exhaust exit direction

nearly vertical 90° 10°

The exhaust muffler is preferably mounted near the air

heater. The direction of flow is optional.

ø 6,5

Fig. 809 Exhaust Pipe Outlet, Installation Position

WARNING

Fig. 808 Exhaust Muffler, Direction of Flow

Any exhaust exit direction other than the one shown in

Fig. 809 may cause fires.

Operation of the air heater is also permitted without

muffler.

Sum of bends:

Combustion air line: max. 270°

Exhaust:

max. 270°

8.6.7 Combustion Air Intake and Exhaust Lines

In order to avoid damage to the dosing pump cable, no

exhaust line may be used for the elongation of the com-

bustion air intake line.

Length of the combustion air intake and exhaust line:

with muffler:

without muffler:

max. 2.0 m

max. 5.0 m

805

8 Servicing

Air Top 2000 S

8.6.8.3 Connection Control Dial

8.6.8 Electrical Connections

The cable loom is prefabricated to connect to the control

dial (rated value transmitter).

8.6.8.1 Connection Air Heater, Control Dial

For plug disconnection pull on terminal plug only

(Fig. 812).

By pulling on the cable loom the terminal plug is

secured (self-locking).

Electrical connection is according to Circuit Diagram

Automatic Control (see Section 7).

For connection of the cable loom the cover (see 9.2.1.1)

of the air heater has to be removed for connecting the

cable loom plug(s) to the control unit. Avoid touching the

control unit strip conductors.

Prior to first operation of the air heater the cover must be

fitted to avoid the loss of heated air (air heater overheat-

ing).

The cable feedthrough may be from left or right.

8.6.8.2 Connection of Power Supply

Fiber optic lens

(operation indicator)

Ideally from the vehicle’s central electrical system.

Fig. 811 Control Dial

An additional blade terminal fuse holder is to be

fitted to protect the heater and harness (supplied

with the heater). The fuse holder should be

installed as close as is practical to the power

source e.g. in the vehicle battery enclosure.

NOTE

The fiber optic lens must be in contact with the

rotary knob.

The fuse holder is constructed of weather resistant

components.

AT 2000 S

F = 15A (12V)

F = 10A (24V)

Fig. 810 Weather Resistant Fuse Holder

Fig. 812 Pulling the Plug

806

Air Top 2000 S

8 Servicing

Fig. 813 Example of an Installation

807

8 Servicing

Air Top 2000 S

8.7 Removal and Installation

8.8 Start-Up

CAUTION

After you have installed the heater, bleed the fuel supply

system carefully.

When the heater is installed it must not be dismantled.

NOTE

8.7.1 Air Heater, Removal and Installation

8.7.1.1 Removal

As a result of the low fuel consumption the heater must

be switched on several times to fill the fuel line.

Conduct a trial of the heater to check all the connections

for leaks and to ensure that they are secure. If the

heater suffers a fault during operation, the fault must be

located and remedied.

1. Disconnect battery terminal leads.

2. Withdraw cover from upper housing shell according

to 9.2.1.

3. Disconnect the wire harness plug from control unit.

4. Disconnect interior air ducts if present.

5. Disconnect cable to dosing pump at cable disconnect.

6. Disconnect fuel inlet on air heater.

7. Disconnect connections of combustion air intake and

exhaust outlet on air heater.

8. Remove four nuts and lock washers on air heater.

9. Remove air heater and discard gasket.

8.7.1.2 Installation

1. Locate air heater with new gasket in installation

position and secure with four nuts and lock washers

(use original Webasto nuts only).

2. Tighten nuts with 6 + 1 Nm.

3. Secure connection for fuel inlet on air heater.

4. Secure connections for combustion air inlet and ex-

haust outlet on air heater.

5. Route cable to dosing pump and connect to dosing

pump.

6. Connect wire harness to control unit.

7. Install cover and secure.

8. Reconnect battery terminal leads.

9. Install interior ducting if present.

10. Bleed fuel supply system (see 8.8).

808

Air Top 2000 S

9. Repair

9 Repair

9.1.2.1 Installation of an External Temperature

Sensor

General

9.1 General

The heater can control the required temperature

perfectly if its temperature sensor is exposed to the air of

the main area of the vehicle. In certain circumstances,

this is not always possible using the temperature sensor

integrated in the control unit due to the installation

circumstances (addition of fresh air). In this case proper

temperature control can be ensured using an external

temperature sensor fitted in the appropriate area.

This section describes the repairs that may be per-

formed on the air heater Air Top 2000 S after it has

been removed from the vehicle.

Any further disassembly will void the warranty.

For reassembly, only components of the proper spare

parts and kits are to be used.

9.1.1 Work on Components after Disassembly

Procedure

1. Select adequate installation location for external

temperature sensor.

CAUTION

All gaskets located between disassembled components

as well as the exhaust outlet seal must always be re-

placed and discarded.

IMPORTANT

Temperature sensor should not be in the direct

line of heated air flow or located in the vicinity of

heating sources (e.g. vehicle’s own heater).

The sensor is to be installed at medium height

in the vehicle interior on surfaces that are as

vertical as possible.

The installation location should not be exposed to

direct sun light.

Do not mount temperature sensor behind curtains or

the like.

9.1.1.1 Cleaning

All components disassembled must be cleaned with

cleaning spirit and subsequently dried with press-

urized air.

All sealing compound must be carefully removed

from components using a suitable tool.

9.1.1.2 Visual Inspection

2. Mount external temperature sensor and route cable

to control unit.

3. Connect connector X9 and install cover.

4. Perform test run and check control behaviour.

Examine all components for damages (cracks, defor-

mation, wear, etc.) and replace as necessary.

Examine connectors and wiring for corrosion, loose

contacts, wrong crimping, etc. and repair as necess-

ary.

Check terminals for corrosion and contacts for

security. Repair as required.

9.1.2 Incorporation of Modifications

NOTE

Control Unit

The continous design improvement of the heaters is in-

tended to optimise their serviceability avoiding failures or

malfunctions.

In general equipment in service may be retrofitted with

available modification kits. In the following that modifica-

tion which may be incorporated easily during maintenace:

Cover

installation of an external temperature sensor for

optimising temperature control of the Air Top 2000 S

(see 9.1.2.1).

External

Temperature Sensor

Connector X9

901

9 Repair

Air Top 2000 S

9.2.1.3 Covers for Heating Air Inlet and Outlet

9.2 Disassembly and Assembly

Both covers (3 and 6, Fig. 901) can be released and

removed by pressing the four detents on top and bottom

using a suitable tool.

9.2.1 Removal of Housing Components/Covers

9.2.1.1 Cover for Electrical Connection

9.2.1.4 Upper Housing Shell

Dependent on the type of installation the cable loom

exits the air heater either on the left or right.

The cover (1, Fig. 901) may be levered off using a blunt

blade in the areas marked X .

NOTE

The covers for the heating air inlet and outlet must be

removed.

9.2.1.2 Grates for Heating Air Inlet and Outlet

The upper shell (2, Fig. 901) can be raised by pulling up.

9.2.1.5 Lower Housing Shell

The grates (5, Fig. 901) can be released from the

covers by twisting and pulling off forwards.

By gently pulling the lower shell (4, Fig. 901) on both

sides in the areas

, you can release the fixing and

the shell can be taken off the motor casing.

1 Cover, Electrical Connection

2 Upper Housing Shell

3 Cover, Heating Air Outlet

4 Lower Housing Shell

5 Grates

6 Cover, Heating Air Inlet

Fig. 901 Removal of Housing Components/Covers

902

Air Top 2000 S

9 Repair

9.2.2 Replacement of Control Unit

9.2.2.1 Removal

9.2.3 Replacement of Temperature Limiter

9.2.3.1 Removal

1. Remove heater from vehicle (see 8.7.1.1).

2. Remove covers for heating air inlet and outlet

(6 and 3, Fig. 901) according to 9.2.1.3.

3. Remove upper housing shell according to 9.2.1.4.

4. Disconnect plug connection (blue) from terminal.

5. Remove screws (4, Fig. 902).

During removal avoid the build-up of static charge (i.e.

do not touch strip conductors).

1. Remove heater from vehicle (see 8.7.1.1).

2. Remove covers for heating air inlet and outlet

(6 and 3, Fig. 901) according to 9.2.1.3.

3. Remove upper housing shell according to 9.2.1.4.

4. Disconnect terminal connections (1, Fig. 902).

5. Remove screws (3) and remove control unit (2)

with bracket (6).

6. Remove temperature limiter (5).

7. Perform work on components after disassembly

(see 9.1.1).

9.2.3.2 Installation

6. Remove screw (7) to separate control unit (2)

from bracket (6) if necessary.

7. Perform work on components after disassembly

(see 9.1.1).

1. Place temperature limiter (5, Fig. 902) into

installation position and secure with screws (4).

Ensure limiter is properly seated.

2. Torque screws to 1.5 ± 0.15 Nm.

3. Connect plug connections (blue) to terminal.

4. Install on upper housing shell and fix in position.

5. Slide on covers for heating air inlet and outlet and fix

in position.

9.2.2.2 Installation

NOTE

6. Install heater (see 8.7.1.2).

During installation avoid the build-up of static charge (i.e.

do not touch strip conductors).

1. Place control unit (2, Fig. 902) in position on

bracket (6) and secure with screw (7).

2. Place control unit (2) with bracket (6) in installation

position and secure with screws (3).

Torque screws to 0.7 ± 0.07 Nm.

3. Connect plug connections to terminal (Fig. 701).

4. Install upper housing shell and fix in position.

5. Slide on covers for heating air inlet and outlet and fix

in position.

6. Install heater (see 8.7.1.2).

7. Check CO₂setting and if necessary, adjust (see 6.2)

903

9 Repair

Air Top 2000 S

Plug Connections

Control Unit

Screw (2)

Temperature Limiter

Bracket

Screw

Fig. 902 Replacement of Control Unit and Temperature Limiter

904

Air Top 2000 S

9 Repair

MAX.

1 Insulation

2 Seal

Fig. 903 Replacement of Combustion Air Fan (Disassembly)

9.2.4 Replacement of Combustion Air Fan

9.2.4.1 Removal

5. Remove insulation (1, Fig. 903)

6. Remove screws (1, Fig. 904).

1. Remove air heater (see 8.7.1.1).

2. Remove control unit (see 9.2.2.1).

3. Remove seal (2 Fig. 903) from lower housing shell

and discard.

7. Withdraw combustion air fan (3) and remove gasket

(2).

8. Perform work on components after disassembly (see

9.1.1).

4. Remove air heater from lower housing shell.

905

9 Repair

Air Top 2000 S

9.2.4.2 Installation

•

Loose wire strands of the mesh must be cut off

to prevent contact with the temperature sensor.

1. Ensure that sealing surfaces on combustion air fan

and on heat exchanger are not damaged.

2. Place new gasket (2, Fig. 904) onto flange of

combustion air fan (3).

3. Place combustion air fan into assembly position and

mount using screws (1). Torque screws (1) to 6 Nm.

Ensure a secure fit between the heat exchanger,

insulating mesh, and the upper housing.

An overly worn, damaged or flattened insulating

mesh must be replaced with a new mesh.

4. Place wire insulating mesh into position on the

heat exchanger (1, Fig. 903).

CAUTION

To ensure the proper function of the heater and to

prevent malfunctions of the temperature sensor,

the following must be observed when installing the

wire insulating mesh:

5. While slightly spreading the lower housing shell,

place over heat exchanger until guide slots

engage with pins on fan housing.

6. Fit new seal (2, Fig. 903) on heater mount base.

7. Install control unit (see 9.2.2.2).

8. Install upper housing shell, air inlet and air outlet.

9. Install air heater (see 8.7.1.2).

10. Check CO₂setting and adjust as required (see 6.2).

•

The wire insulating mesh must be installed as

shown in Fig. 903 to prevent unwanted contact

with the temperature sensor terminals.

Screw (5)

Gasket

Combustion Air Fan

Before assembly always

renew gasket.

Combustion air fan must not be

disassembled any further

Fig. 904 Replacement of Combustion Air Fan (Assembly)

906

Air Top 2000 S

9 Repair

CAUTION

9.2.5 Replacement of Flame Sensor

9.2.5.1 Removal

The glow plug has to be pulled out with utmost care and

must under no circumstances be twisted (danger of

breaking). After a long period of combustion operation

the glow plug may be caked by fuel deposits. In this

case allow penetrating oil to react long enough to free

glow plug for removal.

1. Remove air heater (see 8.7.1.1).

2. Remove control unit (see 9.2.2.1).

3. Remove combustion air fan (see 9.2.4.1).

4. Remove screws (3, Fig. 905) and spoiler (2) for

cable protection.

5. Push out cable grommet (10) towards inside.

6. Carefully bend up locking tab (4) and withdraw flame

sensor (1) from burner insert (5).

7. Loosen screw (13) and remove glow plug (11)

from burner insert.

8. Perform work on components after disassembly (see

9.1.1).

7. Remove flame sensor.

8. Perform work on components after disassembly

(see 9.1.1).

9.2.6.2 Installation

1. Insert new gasket (7, Fig. 905) into heat exchanger

and place combustion tube (6) in assembly position.

2. Ensure that starting air bore is not clogged. If required

clean with wire (approx. 1 mm ø) (see Detail A).

9.2.5.2 Installation

CAUTION

Route cable of flame sensor below fuel pipe.

CAUTION

During glow plug installation observe twist lock (see De-

tail B). That means that the glow has to be inserted so

that the contacts point towards the heat exchanger.

Otherwise there will be the danger of a short circuit.

1. Pass flame sensor (1, Fig. 905) below fuel pipe, feed

connector through opening and push in cable grom-

met (10).

2. Feed cable with protection sleeve through locking tab

and insert flame sensor (1) into burner insert (5).

3. Squeeze locking tab (4).

4. Secure burner insert (5) with four screws (3) and fit

spoiler (2) for cable protection.

5. Pull cable of flame sensor tight.

3. Feed glow plug (11) into burner insert (5) and arrange

cable protective sleeve in slot of burner insert.

CAUTION

When performing the following step ensure that glow

plug is inserted in burner insert fully against stop.

6. Torque all 4 screws (3) to 6 ± 0.6 Nm.

7. Mount combustion air fan (see 9.2.4.2).

8. Install control unit (see 9.2.2.2).

4. Secure glow plug (11) with screw (13). Torque screw

(13) to 0.5 Nm.

9. Install air heater (see 8.7.1.2).

5. Locate burner insert (5) in heat exchanger (8) observ-

ing that cable of flame sensor is positioned below

fuel pipe.

6. Feed connectors of glow plug and flame sensor

through openings and push in cable grommets (9

and 10).

9.2.6 Replacement of Glow Plug

9.2.6.1 Removal

1. Remove air heater (see 8.7.1.1).

2. Remove control unit (see 9.2.2.1).

3. Remove combustion air fan (see 9.2.4.1).

4. Push out cable grommets (9 and 10, Fig. 905)

towards inside.

CAUTION

When performing the following step ensure that there is

a tight fit between grommet (12) and heat exchanger (8).

5. Remove four screws (3) and spoiler (2).

6. Tilt and withdraw burner insert (5) carefully.

7. Secure burner insert (5) using screws (3) and attach

spoiler (2). Torque screws (3) to 4 Nm.

8. Mount combustion air fan (see 9.2.4.2).

9. Install control unit (see 9.2.2.2).

NOTE

Ensure that burner insert (5) has separated from burner

tube (6).

10. Install air heater (see 8.7.1.2).

907

9 Repair

Air Top 2000 S

Flame Sensor

Spoiler

Screw (4)

Locking Tab

Burner Insert

Combustion Tube

Gasket

Heat Exchanger

Cable Grommet

10 Cable Grommet

11 Glow Plug

12 Grommet

13 Screw

Fig. 905 Disassembly of Heat Exchanger (Sheet 1 of 2)

908

Air Top 2000 S

9 Repair

Detail A

Starting Air Bore

Detail B

Twist Lock

Fig. 906 Disassembly of Heat Exchanger (Sheet 2 of 2)

909

9 Repair

Air Top 2000 S

9.2.7 Replacement of Burner Insert,

Combustion Tube, and Heat Exchanger

CAUTION

If the heat exchanger is going to be replaced, the

temperature limiter must also be replaced.

9.2.7.1 Removal

1. Remove air heater (see 8.7.1.1).

2. Remove control unit (see 9.2.2.1).

3. Remove combustion air fan (see 9.2.4.1).

4. Remove flame sensor (see 9.2.5.1).

5. Remove glow plug (see 9.2.6.1).

CAUTION

When performing the following step ensure that fuel

connection is not bent.

6. Remove burner insert (5, Fig. 905).

7. Withdraw combustion tube (6) from heat exchanger

(8) and remove gasket.

8. Perform work on components after disassembly (see

9.1.1).

9.2.7.2 Installation

1. In case a new heat exchanger is fitted, secure

temperature limiter (5, Fig. 902) with screws (4).

Torque screws to 1.5 ± 0.15 Nm.

2. Fit new gasket (7, Fig. 905).

3. Bring combustion tube (6) in assembly position.

NOTE

The burner insert will be secured when installing flame

sensor and glow plug.

CAUTION

When performing the following step ensure that the fuel

connection is not bent.

4. Install glow plug (see 9.2.6.2).

5. Install flame sensor (see 9.2.5.2).

6. Mount combustion air fan (see 9.2.4.2).

7. Install control unit (see 9.2.2.2).

8. Install air heater (see 8.7.1.2).

910

Air Top 2000 S

10 Packaging/Storage and Shipping

10. Packaging/Storage and Shipping

10.1 General

When it is necessary to ship the heater and its components

to a Webasto repair center for inspection or repair, they

are to be cleaned and packaged so that they are protected

against damage during handling, transportation, and

storage.

In storage an ambient temperature of +85 °C and -40 °C

must not be exceeded.

06/2008

1001

Notes

Air Top 2000 S

WEBASTO PRODUCT N.A., INC.

15083 North Road

Fenton, MI 48430

Technical Assistance Hotline

USA:

Canada:

(800) 860-7866

(800) 667-8900

www.techwebasto.com

www.webasto.us

Org. 06/2008 Rev. N/A

P/N LIT9000557A

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