GMC 1976 ZEO 6083 Maintenance Manual page 81

1- 6 4 AIR CONDITIONING SYSTEM
Great emphasis must be placed upon keeping the
system clean. Use plugs or caps to close system com-
ponents and hoses when they are opened to the at-
mosphere . Keep your work area clean.
In removing and replacing any part which re-
quires 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,charge and check the system .
WARNING :
ALWAYS WEAR PROTECTIVE
GOGGLES WHEN WORKING ON REFRIGERA-
TION SYSTEMS . GOGGLES J-5453 ARE IN-
CLUDED IN THE SET OF AIR CONDITIONING
SPECIAL TOOLS . ALSO, BEWARE OF THE DAN-
GER OF CARBON MONOXIDE FUMES BY AV-
OIDING RUNNING THE ENGINE IN CLOSED OR
IMPROPERLY VENTILATED GARAGES .
FOREIGN MATERIAL IN THE
SYSTEM
Whenever foreign material is found in the sys-
tem, it must be removed before restoring the system
to operation.
In the case of compressor mechanical failure,
perform the following operations :
1 . Remove the compressor .
2. Remove the receiver-dehydrator or expansion
tube and discard the unit .
3.
Flush the condenser to remove foreign
material which has been pumped into it .
4. Disconnect the line at the evaporator core inlet
or inlet line to the expansion valve.
Inspect the expansion tube or inlet screen of the
expansion valve for the presence of metal chips or
other foreign material . If the tube or screen is
plugged, replace it . Reconnect the line to the
evaporator core or expansion valve .
5 . Install the replacement compressor .
6. Add the necessary quantity of oil to the sys-
tem. Remember to add the one ounce for the new
receiver-dehydrator.
7 . Evacuate, charge and check system .
"0"
RINGS
REFRIGERANT LINE
CONNECTIONS
Always replace the "O" ring when a connection
has been broken . When replacing the "O" ring, first
dip it in clean refrigeration oil. Always use a backing
wrench on "O" ring fittings to prevent the pipe from
twisting and damaging the "O" ring . Do not over-
tighten . Correct torque specifications are as follows:
CAUTION : Where steel to aluminum con-
nections are being made, use torque for
aluminum tubing.
Removal
* Foot Pounds
HOSE CLAMPS
When hose clamp connections are encountered,
special procedures are necessary for both removal
and installation .
1 . Carefully, with a sharp knife, make an angle
cut in the hose as shown in Figure 31 . This should
loosen the hose so that it may be worked off the
fitting.
2 . Cut off slit end of hose.
CAUTION: Use only approved refrigeration
hose. Never use heater hose. Use extreme
care not to nick or score the sealing beads
when cutting of the hose . Cutting the hose
lengthwise may result in this problem.
Metal
Tube
O.D .
Thread
and
Fitting
Size
Steel
Tubing
Torque*
Alum .
Tubing
Torque*
1/4 7/16 13 6
3/8 5/8 33 12
1/2 3/4
33 12
5/8 7/8 33 20
3/4 1-1/16 33 25