Chevrolet LIGHT DUTY TRUCK (SERIES 10-35) Service Manual page 80

Fig. 1 B -3 0 -D isch a rg in g and C o lle cting Oil From System
W ith o u t C harging S tation J-23 50 0-01
with the tapping valve or tapping manifold adapter.
1. Connect Manifold Gage Set J-5725-04 as shown in
Figure IB-31.
• LOW pressure gage set valve to Accumulator
• Gage set center hose to Refrigerant-12 source
• High pressure gage set valve to vacuum pump
2. TO BEGIN EVACUATION, with Manifold Gage
Set and Vacuum Pump as illustrated in Fig. IB-24
SLOWLY open high and low-side gage valves and begin
vacuum pump operation. Pump the system for 15 minutes
gage reaches 28 "-29" vacuum or more.
after low-side
In all
NOTICE:
specification of 28"-29" of Mercury vacuum is used.
This specification can only be reached at or near sea
level.
For each 1,000 feet above
should be lowered by one inch of mercury vacuum. At
5,000 feet elevation only 23"-24" of vacuum is
required.
If prescribed vacuum cannot be reached, close vacuum
control valve, shut off pump and look for a leak at
connections or pump.
3. When the system is fully Evacuated, close the high-
side gage set valve and turn OFF the vacuum pump.
4. Watch gage to be sure vacuum holds for 5
low-side
(FIVE) minutes. Proceed to Charging if vacuum is held.
5. IF VACUUM DOES NOT H OLD FOR 5
MINUTES, charge system with 1/2 pound Refrigerant-12
and leak check. Discharge system again then repair leak as
necessary. Repeat Evacuation procedure.
Evacuation procedures,
sea level, specification
TO BEGIN CHARGING OF THE C.C.O.T. A/C
SYSTEM
1. Start engine, run with choke open and fast idle speed
reduced to normal idle, set A /C control lever on OFF.
2. With the Refrigerant-12 drum or can(s) inverted,
open R-12 source valve(s) and allow one (1) pound or 1-2
14 oz. can(s) of liquid R-12 to flow into system through
low-side Service fitting on Accumulator (see Figure IB-31).
3. As 1 lb. or 1-2 14 oz. can(s) of liquid R-12 has been
added to system, immediately engage the compressor, by
setting the A /C control lever to N ORM and blower speed
on HI, to draw in the remainder of the R-12 charge.
The Charging operation can be speeded up
NOTICE:
by using a large volume fan to pass air over the
condenser. If condenser temperature is maintained
below charging cylinder temperature, Refrigerant-12
will enter system more rapidly.
4. Shut off R-12 source valve and run engine for 30
seconds to clear lines and gages.
5. With the engine running, remove the charging low-
side hose adapter from the Accumulator Service fitting.
Unscrew rapidly to avoid excess R-12 escape from system.
CAUTION: NEVER REMOVE A GAGE
LINE FROM ITS ADAPTER WHEN LINE
IS CONNECTED
ALWAYS REMOVE THE LINE ADAPTER
FROM THE
DISCONNECT A LINE. DO NOT REMOVE
CHARGING HOSE AT GAGE SET WHILE
ATTACHED TO ACCUMULATOR. THIS
W IL RESULT IN COMPLETE DISCHARGE
OF SYSTEM DUE TO THE DEPRESSED
SCHRADER VALVE IN SERVICE LOW-
SIDE FITTING.
6. Replace protective cap on Accumulator fitting.
7. Leak check system with J-6084 Leak Detector.
the
8. With system fully Charged and leak-checked,
continue to operate system and test for proper system
pressures as outlined under PERFORM ANCE DATA in
C.C.O.T. A /C SYSTEM DIAGNOSTIC PROCEDURE.
ACCUMULATOR ASSEMBLY
The accumulator assembly for the C.C.O.T. system has
a service replacement which includes two O-rings (for the
inlet and outlet connections). The desicant within the shell
is serviced separately - it is part of the sealed
NOT
accumulator assembly.
The accumulator assembly should O N LY be replaced
when:
1. A physical perforation to the accumulator is found
resulting in a leak.
2. The expansion tube (orifice) screen is plugged.
3. The compressor inlet screen is plugged.
4. An evaporator fails because of inside-out (internal
corrosion.
DO NOT REPLACE the accumulator assembly
where:
1. Merely a dent is found in the outer shell of the
AIR CONDITIONING
TO A /C SYSTEM.
SERVICE FITTING TO
LIGHT T R U C K S ER V IC E MANUAL
IB -3 7