SubaruAirConditioningSystems
O
ver the years, Subaru air conditioning systems have taken many different
shapes and sizes, from full manual, cable and vacuum-controlled systems like
those found on Loyale models, to the fully automatic electronically controlled
systems employed by the SVX and some Legacy models. Because of this great
diversity in Subaru air conditioning systems, it would be impossible to tell you
everything there is to know about every single Subaru air conditioning system in
this edition of The End Wrench.
Introduc tion
What we will do instead is to give you a cross-section summary of recent
Subaru air conditioning systems. We’ll show you what’s unique and different
about each system, and describe the best troubleshooting and repair strategies
for these systems.
In compliance with government requirements, all Subaru vehicles manufactured
within the past few years are equipped with R-134a air conditioning systems.
But there are still a large percentage of Subaru vehicles on the road with R-12
refrigerant in their A/ C sytems. We’ll explain how to safely handle R-12 and
R-134a refrigerants, and we’ll also explain your repair and retrofit options
when a Subaru equipped with an R-12 air conditioning system comes to your
shop for repairs.
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SubaruAirConditioningSystems
Fast Idle Control Device (A/C Idle Air Control)
On manual transaxle equipped Justy vehicles, the FICD is incorporated in the
idle-up system. Proper adjustment and operation is outlined in Service Bulletins
02-70-89 and 02-72-89.
On ECVT equipped carbureted vehicles an air/ fuel bypass control system
performs the FICD function. The ECVT air bypass control system consists of
an air bypass valve, an adjusting screw, and an air bypass solenoid. The system is
designed to increase idle speed whenever the A/ C relay is activated by supplying
additional air/ fuel into the intake manifold.
Bypass air enters through the air horn on the secondary side.
The airflow is regulated by an adjusting screw. When the bypass valve opens,
bypass air/ fuel enters the manifold below the secondary throttle plate.
When the adjusting screw is turned clockwise, bypass air/ fuel is reduced and
the idle speed is lowered. When the adjusting screw is turned counter clockwise,
bypass air/ fuel is increased and the idle speed is increased.
Bypass Adjusting Screw
(ECVT)
Note: Always refer to the appropriate Justy model year Subaru Service Manual
sections 2-2 and 2-6 for the proper ECVT FICD adjustment procedures
and specifications.
TBI system equipped Loyale vehicles control the FICD function through the
ECM, the idle air control valve (IAC), and the A/ C switch. The air conditioning
ON/ OFF switch is an input to the ECM. The ECM operates the idle air control
valve (IAC) to adjust the idle speed to compensate for the increased compressor
load. No adjustment is required.
On all model year Loyale and XT MFI vehicles, an FICD solenoid incorporated
in the throttle body provides the increase in idle speed. The throttle body includes
an adjustment screw for adjusting the FICD specification.
All Legacy, SVX and XT6 vehicles use an idle air control valve to provide the
FICD function. The valve opens a port during A/ C operation which admits
additional air into the induction system.
Impreza vehicles use a solenoid which initially compensates for the increased
compressor load when the air conditioning system is switched ON. The A/ C IAC
then compensates to maintain engine speed at target RPM.
TBI (IAC)
Note: The Impreza FICD solenoid is set at the factory and should not require
adjustment. Any changes to the adjustment can affect driveability and vehicle
emissions during cold engine operation.
Justy MFI vehicles increase idle speed by admitting additional air into the air
collector assembly through the FICD solenoid which is opened by a signal from
the MFI control unit.
MFI/TBI FICD Operation
rench
A/C Idle Air Systems
Impreza FICD
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Troubleshooting and Servicing
Six Step Troubleshooting
The following six step method of troubleshooting will save time and effort in the
diagnosis and analysis of air conditioning problems. It provides a logical approach
to solving the problem, not just treating the symptoms. The steps are as follows:
➊ Verify the problem (Operational check)
Check that the problem does exist.
Are components inoperable or malfunctioning?
➋ Determine related symptoms (Operational check)
Identify other symptoms that exist.
Are other circuits and components affected?
Do the related symptoms always occur with the primary symptom?
➌ Isolate the problem
Use the split half technique, the wiring diagrams, the troubleshooting
trees, appropriate model year service manuals, and manufacturer’s
manuals to locate the problem.
➍ Identify the cause of the problem
Is a circuit grounded?
Proper vacuum not available?
Belt alignment and/ or tension improperly adjusted, or is a
component defective?
➎ Repair and/or replace
Defective wiring, vacuum lines, and components as required.
Confirm proper adjustment of components as required.
➏Verify operation
Check the system to verify that the problem has been solved.
Ensure that all system components operate properly under standard
operating conditions according to technical specifications.
Also check related systems for proper operation.
Quick Touch Method
An important step in troubleshooting air conditioning systems is to use the
quick touch method. Very briefly touch the components and tubing on the high
side and the low side of the system. High side components should feel warm
or hot to touch, while the low side components should feel cool to the touch.
Exercise caution when performing this procedure on high side of the system. The
tubing and components may be hot enough to cause minor burns. Do not touch
or hold for extended periods of time.
Note: If a component on the high side of the system located before the Thermal
Expansion Valve is cool or cold, this is an indication of a restriction.
Quick Touch Method
Servicing
Manifold Gauges
The manifold gauges measure the pressures of the low side or suction side and
the high side or discharge side of the system. The gauges are calibrated in “psi for
pressure” and “inches of mercury for vacuum”. Note that zero (0) psi is equal to sea
level or 14.7 psi, or the pressure at the altitude level at which the gauge is being used.
The gauge set consists of the valve body, the connectors for the low pressure,
charge or evacuation, and high pressure hoses, and the gauges. The service valves
are infinitely adjustable between fully open and fully closed.
Manifold Gauges
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SubaruAirConditioningSystems
To connect the manifold gauge set to the system:
➊ Fully close both of the manifold valves.
➋ Remove the compressor service valve caps.
➌ Connect the high and low pressure hoses to the service valves.
Note: Some refrigerant gas will be discharged as the hoses are connected to the
service valves. This is normal, however, you should attempt to connect the
hoses as quickly as possible to prevent excess refrigerant loss and air from
entering the system.
Note: Start vehicle engine and follow the directions concerning idle speed, etc.,
contained in the appropriate model year Subaru Service Manual.
Note: Federal Law requires that all A/C service hoses be equipped with check
valves at or near the service hose connections. These check valves prevent
refrigerant in the hoses from escaping to the atmosphere.
To disconnect the gauge set from service valves:
➊ Quickly disconnect the charging hoses from the service valves.
➋ Always disconnect the low side while the engine is running.
➌ Disconnect the high side with the engine OFF and after the pressure
has stabilized.
Manifold gauge interpretation takes some practice and must be completed
with consideration of the other symptoms and potential problems that have been
identified in the system.
Precautions
➊ Wear protective clothing and eyewear, do not allow skin to come in direct
contact with refrigerant.
➋ Do not store or allow refrigerant containers to exceed 52 degrees C.
(126 degrees F.)
➌ Do not use refrigerant in confined spaces with poor ventilation.
➍ Do not use R-12 refrigerant in the presence of an open flame.
➎ Do not steam clean system.
➏ Do not drop refrigerant containers or otherwise cause the container
to rupture.
➐ Follow proper procedure while connecting/ disconnecting hoses of
manifold gauges, vacuum pump, oil separator, and charging systems.
➑ Open and close manifold gauge valves carefully.
➒ Exercise caution while working around drive belts, pulleys, and other
moving components of an operating air conditioning system.
➓ Ensure the proper level and type of compressor oil in system.
Note: Do not introduce compressed air into R-134a components.
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General Preparations
Always conduct a visual inspection of the air conditioning system to identify
any damage, excessive wear, refrigerant leaks (oil residue), improper belt adjust-
ment, improper pulley alignment, and plugged condenser cooling fins.
Note: Never use water to clean the condenser or radiator fins. Using compressed
air is the approved method.
Observe the refrigerant flow through the receiver/ dryer sight glass (if
equipped), use the correct gauges to check all systems, verify all system compo-
nents and controls are operable, check for loose fittings, replace defective, worn, or
damaged drive belts, and repair system leaks.
Note: The use of the sight glass alone to determine system charge level can be
misleading. Normally operating and correctly charged variable displacement
compressors and R-134a systems will have bubbles showing in the sight
glass under certain conditions.
Discharging
Caution: Refrigerant R-12 has been identified as a compound which causes
damage to the ozone layer. It is unlawful to discharge R-12 into the atmosphere.
Subaru of America encourages you to handle R-12 in a responsible and safe
manner, and according to Federal EPA guidelines and any local and state regulations.
Always follow approved recovery/ recycling procedures and utilize approved
recovery/ recycling equipment.
Discharging and recovery of the system refrigerant is required before replacement
of major components of the system. It is also required when the system has a leak,
or for the replacement of refrigerant oil. Discharging and recovery of the system
refrigerant is the first step in preparing for major servicing, repair,
or replacement of components; the second step is evacuation.
Evacuating
Evacuating the system removes air and moisture from the system.
Discharge and recover the system refrigerant first; then follow the
steps listed below to evacuate the system:
•
•
Fully close both valves of the manifold gauge set.
Connect a vacuum pump to the center charging hose of
the manifold gauge set.
•
•
•
Start the vacuum pump.
Open the low- and high pressure valves slowly.
When the pressure reading has reached approximately 29.00
in Hg, fully close both valves.
Evacuating The System
•
•
Stop the vacuum pump.
Wait 10 minutes, the pressure reading should not change.
If it changes, there is a leak in the system.
Elevation
m (ft)
Vacuum of System
mm Hg, in Hg
710 27.95
685 26.97
660 25.98
635 25.00
Note: Certain types of system leaks such as loose fittings may not
be discovered using this method. Always recheck the system
with a leak detector after the system is charged.
0 (0)
300 (1,000)
600 (2,000)
900 (3,000)
Note: Values show readings of the low-pressure gauge.
Elevation/Pressure Relationship
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SubaruAirConditioningSystems
Charging
Charging the system is required after servicing, repair or replacement of system
components, or to locate a leak when there is no refrigerant in the system. Follow
the steps listed below to charge the system:
• Leak detection of a pressurized system is required to locate an otherwise
unidentifiable leak in a discharged system or when the system was
dicharged/ evacuated for repairs.
• The proper procedure is to:
- Connect the manifold gauges or ACR-4 to the system.
- Attach the center charging hose to the refrigerant source.
- Charge the system initially with .5 -.75 lbs (0.226-0.34 kg).
Note: Refer to the appropriate model year Subaru Service Manual or air conditioning
manufacturer’s instructions for charging details, pressures, and system
capacities. Use an electronic leak detector such as a pump-style halogen
dual-gas type.
- If a leak is detected, recover the remaining refrigerant and repair
the leak.
- If no leak is detected, continue charging the system.
- When charging of the system has been completed, close the manifold
gauge valves, and manually rotate the compressor several turns to
distribute any trapped refrigerant oil before the clutch is engaged.
- Check again for refrigerant leaks with an approved leak detector.
- Conduct a performance test.
- Upon successful completion of the performance test, disconnect the
high and low-pressure hoses from the service valves.
- Replace the valve caps to the service valves.
Charging/Leak Detection
Refrigerant is colorless and odorless. You must use a leak detector to locate a
leak and determine the size of the problem.
Use of a halogen pump style electronic leak detector is recommended over
other types of detectors. Electronic leak detectors usually buzz or squeal in the
presence of refrigerant. Always follow the leak detector manufacturer ’s instruc-
tions for proper use. It is Subaru policy to not use flame-type detectors, because
harmful gasses may be emitted when using these types of detectors.
Oil Discharging and Refill Procedure
Discharge the compressor oil when the quality of the refrigerant oil is unsatis-
factory or for repair of the compressor. Turn the compressor upside down, and
pour the oil out of the compressor. Most compressors drain oil from both the inlet
and outlet ports. The DIESEL KIKI variable dis-
placement compressor drains (and fills) oil
through a drain plug hole located in the center
of the case. Always refer to the appropriate
model year Subaru Service Manuals and the
A/ C manufacturer ’s instructions. Be sure to
record the amount of oil discharged.
Note: New compressors contain enough oil for a
complete dry system. When replacing a new
compressor on an existing system, the old
compressor must be drained and the oil
quantity measured. Then drain the new
Oil Discharging
compressor and measure the amount of oil.
Refill the new compressor with the same quantity
of oil as was removed from old compressor.
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SubaruAirConditioningSystems
Fill the compressor with the proper amount of the correct type refrigerant oil.
Use of the incorrect type of compressor oil may result in damage to the com-
pressor. Refer to Subaru Service Bulletin number 10-37-84, dated 12-12-84, for
compressor oil specifications for Matsushita (Panasonic), Hitachi, Lone Star and
other compressor types. Always manually rotate the compressor several turns to
confirm proper operation after filling with refrigerant oil.
Note: The variable displacement Calsonic and DIESEL KIKI compressors
may only be filled with special V-5 compressor oil, (D-9OPX). Any
contamination with other types of compressor oils will cause
compressor damage. Never substitute or cross-contaminate R-12
compatible compressor oil with R-134a compatible compressor oil.
Refer to the Oil Charge Table found in Section 4-7 of the appropriate model
year Service Manual. This can be a useful tool to determine the proper procedure
to follow and to determine the amount of refrigerant oil to add or replace to the
compressor after servicing, repairing, or replacing major system components.
Always manually rotate the compressor several turns to confirm proper operation.
Oil Refill
Performance Testing
Test Conditions
•
•
•
•
•
The vehicle must be indoors or in the shade.
Doors should be closed, all windows open.
Hood open.
Connect the manifold gauge.
Set the mode switch to the A/ C MAX position. (On variable displacement
compressor system set the A/ C controls to high blower and normal A/ C.)
Note: When servicing variable displacement compressors refer to Service Bulletin,
10-52-89, dated 07-28-89, for complete compressor diagnostic information.
•
•
•
Set the temperature control to COLD.
Start the engine and idle at 1,500 RPM.
Operate for approximately 10 minutes, then observe the high and the low
pressure levels.
An essential step of the performance test is measuring the temperature of the
inlet air at the blower and the temperature of the outlet air at the vent grills. The
temperature difference should be within specifications for the system. System
temperatures will vary with changing conditions, such as high ambient air
temperature, humidity, and altitude.
Temperature Measurement
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SubaruAirConditioningSystems
Performance Test Results
➌ Lower than normal
pressures indicate:
Standard Compressor Systems
➊ System performs to
specifications; test complete
➋ Higher than normal
pressures indicate:
—System is undercharged, or
—Compressor is NOT
changing to minimum stroke
➍ Switch system “ON” and
“OFF”
—Compressor has shifted
to minimum stroke
• Stop engine
• Wait ten (10) minutes, retest
—System is undercharged
• “Clunking” sound is normal
while charging system
—Compressor is defective
—Restriction of air across
condenser
—Defective cooling fan(s)
—Refrigerant overcharge
—Restriction in system
—Air in system
➎ If high and low side
pressures remain equal
—Extreme System
undercharge, or
—Defective compressor
Control Valve Testing—
Variable Displacement
Compressor
—Moisture in system
➌ Lower than normal
pressures indicate:
Note: The clutches on the variable
displacement Calsonic and
DIESEL KIKI compressors are
not serviceable. Always refer to
the current Subaru Service
➊ Bring compressor to the
minimum stroke position
—Open hood and windows
—Set engine speed to fast idle
—Set blower speed to low
—Set A/ C control to A/ C MAX
➋ Suction pressure should
be 25-35 psi
Note: When inlet air temperature
to evaporator is “LOW”, the
discharge pressure may appear
to be excessively “LOW” and
bubbles may be seen in sight
glass. This condition is normal.
➌ Lower than normal
—System is undercharged
—Compressor is defective
Bulletins for possible future
changes to this procedure.
Variable Displacement
Compressor Systems
➊ System performs to
specifications, test complete
➋ Higher than normal
pressures indicate:
—Restriction of air across
condenser
—Defective cooling fan(s)
—Refrigerant overcharge
—Restriction in system
—Air in system
pressure indicates:
—Moisture in system
Number Date
Title
Remarks
Number Date
Title
15-42-87
15-44-87
02-70-89
05-18-87
Accessory A/ C
Justy S0A332A105
10-57-90
10-58-90
10-59-90
05-29-90 A/ C Compressor Inspection
05-30-90 Thermoprotector Service Procedure
05-26-87
08-24-89
Accessory AC
(S0A332A1 05)
Install on (4EAT)
07-06-90 Thermoprotector Testing
Procedure Clarification
Idle Speed
Adjustment Procedure
for MT/ ECVT
10-60-90
10-61-91
10-62-91
08-14-90
Automatic Climate Control
Diagnostic Information
02-72-89
05-07-86
Idle Speed
Adjustment Procedure
for MT/ ECVT
Addendum to Service
Bulletin #02-70-89
07-02-91 Removal and Recycling of
Refrigerant R-1 2
09-20-91
Wynn’s Justy A/ C
10-49-88
10-50-89
08-04-88
05-29-89
Fresh/ Circ Air Lever
Not Holding Position
SOA329A110 & S0A329A112
10-63-93
10-64-93
10-65-94
10-66-94
04-12-93
11-08-93
03-08-94
06-17-94
R-134a Refrigerant Handling Procedures
Heater Vent Door Binding Or Leaking Air
Proper Oils For Subaru A/ C Systems
Heater Gears
(87-89 ‘L’ Series)
10-51-89
10-52-89
05-29-89
07-28-89
Compressor Oil (Legacy)
V-5 Compressor & A/ C
R-12 and R-134a Air Conditioning System
Handling Procedures
System Service Information
10-53-89
10-55-90
10-18-89
01-29-90
A/ C System Servicing
10-67-94
11-11-94
Clicking Noise From The Heater
Mode Door Actuator
Discontinued Shorting Loop
For A/ C Cut Relay
rench
10-68-96R 07-01-98
Air Conditioning Retrofit Procedures
R-12 to R-134a
10-56-90
01 -29-90 Heater Gears - ‘87 to ‘89
‘L’ Series & XT Models
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