Chevrolet 10 Series 1968, Service Manual

Page: 53 / 713

HEATER AND AIR CONDITIONING 1A-22
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 or a major
leak, add the same amount to the replacement
compressor.
c. If the amount drained is less than 1-1/2 oz.
and the system appears to have lost an excessive
amount of oil, add 6 fluid oz. of clean refrigera­
tion 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 11 fluid oz. of new refrigeration oil to the
replacement compressor.
5. Add additional oil in the following amounts for any
system components being replaced.
E v a p o ra to r......................................... 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
Frigidaire 525 Viscosity refrigeration oil and add as
follows:
1. Connect the Charging Station low pressure gauge
line to the low pressure gauge fitting on the P.O.A.
valve.
2. Connect the Charging Station high pressure gauge
line to the compressor muffler.
3. Disconnect the high pressure line from the gauge
set, make certain that the line is clean, and place
the end in a graduated oil container.
4. Pour enough refrigerant oil in 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 the high pres­
sure line to the gauge set. Open the high pressure
valve and evacuate the system through the high and
low pressure side of the system. Complete the
charging operation as outlined in Step 6 under
“ Evacuating and Charging System” .
COMPONENT REPLACEMENT AND MINOR REPAIRS
PREPARING SYSTEM FOR
REPLACEMENT OF COMPONENT PARTS
A ir conditioning, like many other things, is fairly
simple to service once it is understood. However, there
are certain procedures, practices and precautions that
should be followed to prevent costly repairs, personal
injury or damage to equipment. For this reason it is
strongly recommended that the preceding information in
this section be studied thoroughly before attempting to
service the system.
Great emphasis must be placed upon keeping the sys­
tem clean. Use plugs or caps to close system components
and hoses when they are opened to the atmosphere. Keep
your work area clean.
In removing and replacing any part which requires
unsealing the refrigerant circuit the following operations,
which are described in this section, must be performed
in the sequence shown.
1. Purge the system by releasing the refrigerant to the
atmosphere.
2. Remove and replace the defective part.
3. Evacuate and charge the system with R-12.
C A U TIO N : Always wear protective goggles
when working on refrigeration systems. Goggles
J-5453 are included in the set of air conditioning
special tools. Also, beware of the danger of
carbon monoxide fumes by avoiding running the
engine in closed or improperly ventilated
garages.
FOREIGN MATERIAL IN THE SYSTEM
Whenever foreign material is found in the system,
it must be removed before restoring the system to
operation.
In the case of compressor mechanical failure, perform
the following operations:
CHEVROLET TRUCK SERVICE MANUAL