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HEATER AND AIR CONDITIONING 1A-45
• A very badly leaking compressor seal.
• Collision damage to the system components.
As a quick check on compressor oil charge, with the
engine off, carefully crack open the oil drain plug on the
bottom of the compressor. If oil comes out, the com-
pressor has the required amount of oil To further check
the compressor oil charge, should the above test show
insufficient oil, it is necessary to remove the compressor
from the vehicle, drain and measure the oil.
Checking Compressor Oil Charge
1. Run the system for 10 minutes at 500-600 engine
rpm with controls set for maximum cooling and
high blower speed.
2. Turn off engine, discharge the system, remove
compressor from vehicle, place it in a horizontal
position with the drain plug downward. Remove the
drain plug and, tipping the compressor back and
forth and rotating the compressor shaft, drain the
oil into a clean container, measure and discard the
oiL
3. a. If the quantity drained was 4 fluid oz. or more,
add the same amount of new refrigerant oil to
the replacement compressor.
b. If the quantity drained was less than 4 fluid oz.,
add 6 fluid oz. of new refrigeration oil to the
replacement compressor.
c. If a new service compressor is being installed,
drain all oil from it and replace only the amount
specified in Steps 3a and 3b above.
d. If a field repaired compressor is being installed,
add an additional 1 fluid oz. to the compressor.
4. In the event that it is not possible to idle the com-
pressor as outlined in Step 1 to effect oil return to
it, proceed as follows:
a. Remove the compressor, drain, measure and
discard the oil.
b. If the amount drained is more than 1-1/2 fluid
oz. and the system shows no signs of a major
leak, add the same amount to the replacement
compressor.
c. If the amount drained is less than 1-1/2 fluid oz.
and the system appears to have lost an excessive
amount of oil add 6 fluid oz. of clean refrigeration
oil to replacement compressor, 7 fluid oz. to a
repaired compressor.
If the oil contains chips or other foreign ma-
terial, replace the receiver-dehydrator and flush
or replace all component parts as necessary. Add
the full specified volume of new refrigeration oil
to the system.
5. Add additional oil in the following amounts for any
system components being replaced.
Evaporator
3 fluid oz.
Condenser . . . . . . . . . . . . . 1 fluid oz.
Receiver-Dehydrator . . . . . . . 1 fluid oz.
NOTE:
When adding oil to the compressor, it
will be necessary to tilt the rear end of the
compressor up so that the oil will not run out
of the suction and discharge ports. Do not set
the compressor on the shaft end.
Adding Oil to the System
The system should be completely assembled and un-
charged before adding oil. Use only uncontaminated
refrigerant oil (525 viscosity) and add as follows:
1. Connect the low pressure line from the gauge set
to the low pressure gauge fitting on the P.O.A.
valve (Four-Season) or low pressure fitting on the
compressor connector Mock (Universal System).
2. Connect the high pressure line from the charging
station gauge set to the compressor muffler or high
pressure side of the connector block.
3. Disconnect the high pressure line from the gauge set,
make certain that the line is clean, and place the
end in a graduated container.
4. Pour enough refrigerant oil into the container so
that the required volume may be drawn into the
system by the high pressure hose.
5. Close the high pressure valve at the gauge set,
and open the low pressure valve.
6. Operate the vacuum pump to drop the pressure within
the system and cause atmospheric pressure to force
oil through the high pressure line into the system.
When the oil level has dropped the required volume,
pull the line out of the oil container and continue
vacuum pump operation to force the oil contained
in the line into the system.
7. Shut off the vacuum pump and connect ttye high
pressure line to the gauge set. Open the high
pressure valve and evacuate the system through
the high and low pressure sides of the system.
Complete the charging operation as outlined in Step
10 under "Evacuating and Charging System".
COMPONENT REPLACEMENT AND MINOR REPAIRS
REFRIGERANT LINE CONNECTIONS
" O " Rings
Always replace the " O " ring when a connection has
been opened. When replacing the " O " ring, first dip it
in refrigeration oil. Always use a backing wrench on
" O " ring fittings to prevent the pipe from twisting and
damaging the " O " ring. Do not overtighten. Correct
torque specifications are as follows:
Metal
Tube
O.D.
1/4
3/8
1/2
5/8
3/4
Thread and
Fitting
Size
7/16
5/8
3/4
7/8
1-1/16
Steel
Tubing
Torque*
13
33
33
33
33
Alum.
Tubing
Torque*
6
12
12
20
25
* Pound Feet
CHEVROLET CHASSIS SERVICE
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