C O M P Re Sso - GMC 1982 Light Duty Truck Service Manual

IB -30 AIR CONDITIONING
can(s) following instructions included with the tapping
valve or tapping manifold adapter.
1. Connect M anifold Gage Set J-5725-04 as follows. Also
see Fig. 1 B-12.
• Low pressure gage set valve to A ccum ulator fitting
• Gage set center hose to R e frig e ra n t-12 source
• High pressure gage to vacuum pum p
2. To begin evacuation of the A /C system, with M anifold
G age Set and Vacuum Pump as illustrated in Fig. 1B-
13, S L O W L Y open high and low-side gage valves and
begin vacuum pum p operation. Pum p the system until
the low-side gage reaches 71 1.2 - 736.6m m (28 to 29
in.) m ercury (vacuum ) or more.
N ote th a t in all
specification of 711.2 - 736.6m m (28 to 29 in.) of
m ercury vacuum is used. This specification can only be
reached at or near sea level. For each 304.8m (1,000
feet) above sea level, specification should be lowered by
one inch of vacuum . A t 1524m (5,000) feet elevation
only 584.2 - 609.6m m (23 to 24 in.) of m ercury
(vacuum ) is required.
If prescribed m ercury (vacuum ) cannot be reached,
close vacuum control valve, shut off pum p and look for
a leak at connections or pump.
3. W hen the gage reaches prescribed vacuum , the system
is fully evacuated. Close the high-side gage set valve
and turn O F F the vacuum pump.
4. W atch low-side gage to be sure vacuum holds for five
(5) minutes. If vacuum is held, disconnect vacuum hose
at gage set and then proceed to charging.
5. If vacuum does not hold for five (5) m inutes, charge
system with 420 ml (1 /2 lb.) R efrig eran t-12 and leak
check. D ischarge system again then repair leak as
necessary. R epeat Evacuation procedure.
TO BEGIN C H A R G IN G OF THE CCOT A /C
SYSTEM
1. S ta rt engine, run with choke open and fast idle speed
reduced to norm al idle, set A /C control lever on O FF.
2. W ith the R efrig eran t-12 drum or 420 ml (14 oz.)
can(s) inverted, open R e frig e ra n t-12 source valve(s)
and allow 480 ml (one (1) pound) or one 420 ml (14
oz.) can of liquid R e frig e ra n t-12 to flow into system
through low-side Service fitting on A ccum ulator (R efer
to Fig. 1 B-12).
3. As soon as 480 ml (1 lb.) or one 420 ml (14 oz.) can of
liquid R e frig e ra n t-12 has been added to system ,
im m ediately engage the compressor, by setting the
A /C control lever to N O R M and blower speed on HI,
to draw in the rem ainder of the R efrig eran t-12 charge.
The C harging operation can be speeded up by using a
large volume fan to pass air over the condenser. If
condenser tem p eratu re is m aintained below charging
cylinder tem perature, R e frig e ra n t-12 will enter system
more rapidly.
4. S hut off R e frig e ra n t-12 source valve and run engine for
30 seconds to clear lines and gages.
5. W ith the engine running, remove the charging low-side
hose adap ter from the A ccum ulator Service fitting.
Unscrew rapidly to avoid excess R e frig e ra n t-12 escape
from system.
E vacu atio n procedures,
C A U TIO N : N ever rem ove a g a g e line from its
a d a p te r w h e n line is connected to A /C system.
A lw ays rem ove the line a d a p te r from the service
fittin g to disconnect a lin e . Do not rem ove
ch arg in g hose a t g a g e set w h ile a tta c h e d to
accum ulator. This w ill result in com plete discharge
of system due to the depressed schrader valve in
service low -side fittin g , a n d m ay cause personal
injury due to escaping R e frig e ra n t-12.
6. Replace protective cap on A ccum ulator fitting.
7. T urn engine off.
8. Leak check system with .1-6084 Leak Detector.
9. S tart engine.
the 8. W ith system fully C harged and leak-checked, continue
to operate system and test for proper system pressures
as outlined under P E R F O R M A N C E C O N D IT IO N S
A N D P E R F O R M A N C E
T E M P E R A T U R E D A TA in C h arts 1 B-4 and 1 B-5.
A C C U M U LA TO R ASSEMBLY
The accum ulator assembly for the C C O T system has a
service replacem ent which includes two " O " rings (for the
inlet and outlet connections). The desicant within the shell is
NOT serviced sep arately - it is p a rt of the sealed
accu m u lato r assem bly. See C C O T R e frig era n t Oil and
D istribution for presence of re frig e ra n t oil and service
conditions when the accum ulator m ust be removed from the
vehicle to m easure the am ount of oil present inside the
accum ulator.
The accum ulator assembly should O N L Y be replaced
when:
1. A physical perforation to the accum ulator is found
resulting in a leak.
2. T he expansion (orifice) tube screen experiences
continued or repeated plugging.
3. T he com pressor
compressor).
4. An ev ap orator fails because of inside-out (in tern al
corrosion.
DO N O T R E P L A C E the a c cu m u lato r assem bly
where:
1. M erely a den t is found in th e o u ter shell of the
accum ulator.
2. A vehicle is involved in a collision and no physical
perforation to the accu m u lato r is found. An open
refrigerant line should be capped or have a plastic bag
tightly taped around it.
A C C U M U LA TO R REPLACEMENT
1. Disconnect battery ground cable.
2. Discharge system of refrigerant.
3. Disconnect accum ulator inlet and outlet connections.
C ap or plug open lines im m ediately.
4. Rem ove accu m u lato r a tta c h in g screw s and check
am ount of oil in accum ulator and install this am ount of
fresh 525 viscosity refrigerant oil into new accum ulator
plus 60 ml (2 oz.)
5. Install new accu m u lato r, using clean 525 viscosity
refrigerant oil on " O " rings.
6. Evacuate and recharge system.
P R E S S U R E -
inlet screen is plugged (A6