Subaru 1600 Service Manual page 573

HEATING VENTILATING AND AIR-CONDITIONING SYSTEM ,
condition, the compressor oil level
check is unnecessary.
When checking the level of compressor
oil or when replacing any component
part of the system, use the following
service procedure. This facilitates to
return oil to compressor.
1) Operate compressor at engine
speed from 1,000 rpm to 1,500 rpm
with controls set for maximum cooling
and high blower speed for about 10
minutes in order to return compressor
oil to compressor.
2) Stop the engine and discharge
refrigerant of system and then remove
compressor from the car.
3) When exchanging the compressor
for new one which contains 150 cm
3
(ISO cc, 9.15 cu in) oil, drain 80 cm
3
(80
cc,
4.88
cu in) oil from it or
adjust the amount of oil to the same
of the removed compressor.
4) When exchanging for a service
compressor which contains 70 cm
3
(70 cc, 4.27 cu in) oil, install it with-
out any adjusting.
5) When exchanging a cooling unit,
pour
SO
cm
3
(SO
cc, 3.05 cu in) oil to
the compressor from the suction hose
after installing the cooling unit.
If compressor is inoperative due to
defective compressor or heavy loss of
refrigerant, exchange the compressor
through the procedure from 2 to S.
10) Performance Test
The cooling performance of the air
conditioner changes considerably with
changes in surrounding conditions.
Testing must be performed using the
correct method. This test is used to
judge whether system is operating cor-
rectly 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 lever to AIC MAX posi-
tion.
6) Set temperature control dial to
COLD position.
7. Set blower to its highest speed.
8. Start the engine and hold engine
speed at 1 ;500 rpm.
9) After the air conditioner has been
operated for about 10 minutes, meas-
ure system pressures at high-pressure
(discharge) side and low-pressure (suc-
tion) side.
10) Measure the temperatures of inlet
air to blower and outlet air at the
grilles.
11) Measure the temperature and
humidity of the ambient air at a point
1 m (3.3 ft) front of condenser. How-
ever, a dry bulb and wet bulb must
not be placed in direct sunlight.
12) Check for any abnormalities by
comparing the test results with stand-
ard pressure in "Performance Chart".
NOTE:
a. The pressure will change in the
following manner with changes in
conditions:
• When blower speed is low, dis-
charge pressure will drop.
• When the relative humidity of in-
take air is low, discharge pressure
will drop.
b. The temperature will change in the
13-28
following manner with changes in
conditions:
When the ambient air temperature
is low, the oudet 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
"Troubleshooting".
11) Refrigerant Leaks
If leaks are noticeable, leaky parts
should be repaired. Then system
should be fllied with refrigerant. Do
not operate compressor with refriger-
ant level exceSSively low.
If this caution is neglected, a burnt
compressor will result since heavy loss
of refrigerant usually indicates heavy
loss of compressor oil.
If system has been exposed to atmo-
sphere 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
conn~ction
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 retightened, discharge
refrigerant from system, disconnect
the fittings, and check its seating face
for damage. Always replace even if
damage is slight.
3) Check compressor oil and add oil
if required.
4) Charge refrigerant and recheck
for gas leaks. If no leaks are found,
evacuate and charge system.