Subaru XT 1988 Service Manual page 1043

AIR CONDITIONING SYSTEM
4-7
PERFORMANCE TEST
The cooling performance of the air conditioner changes con-
siderably with changes in surrounding conditions. Testing must
be performed using the correct method. This test is used to
judge whether system is operating correctly and can also be
used as a guide in checking for problems.
1) Park the car indoors or in the shade.
2) Open all the windows of the car fully. However, close the
doors.
3) Open the hood.
4) Connect manifold gauge to high· and low·side service
valves of the system. Refer to "Handling Manifold Gauge".
5) Set mode switch to AIC MAX position.
6) Set temperature control lever to COLD position.
7) Start the engine and hold engine speed at 1,500 rpm.
8) After the air conditioner has been operated for about 10
minutes, measure system pressures at high-pressure (discharge)
side and low-pressure (suction) side.
9) Measure the temperatures of inlet air to blower and outlet
air at the grilles.
10) Measure the temperature and humidity of the ambient air
at a point 1 m (3.3 tt) front of condenser. However, a dry
bulb and wet bulb must not be placed in direct sunlight.
11) Check for any abnormalities by comparing the test
results with standard pressure in "Performance Chart".
a. The pressure will change in the following manner with
changes in conditions:
• When blower speed is low, discharge pressure will drop.
• When the relative humidity of intake air is low, discharge
pressure will drop.
b. The temperature will change in the following manner
with changes in conditions:
When the ambient air temperature is low, the outlet air
temperature will become low.
If the test reveals that there is any abnormality in system
pressure, isolate the cause and repair by reference to "Trouble-
shooting".
21
REFRIGERANT LEAKS
If leaks are noticeable, leaky parts should be repaired. Then
system should be filled with refrigerant. Do not operate com-
pressor with refrigerant level excessively low.
If this caution is neglected, a burnt compressor will result
sinGe heavy loss of refrigerant usually indicates heavy loss of
compressor oil.
If system has been exposed to atmosphere for an extended
period of time, receiver drier must be replaced. If leaks are
slight and no air is present in system, add refrigerant as
necessary. To detect leaks, refer to relative topics under
"Checking for Leaks". Here is how leaks are stopped.
1) Check torque on the connection fitting and, if too loose,
tighten to the proper torque. Check for gas leakage with a leak
detector.
2) If leakage continues even after the fitting has been re-
tightened, discharge refrigerant from system, disconnect the
fittings, and check its seating face for damage. Always reo
place even if damage is sl ight.
3) Check compressor oil and add oil if required.
4) Charge refrigerant and recheck for gas leaks. If leaks are
found, evacuate and charge system.