GMC 1982 Light Duty Truck, Руководство по обслуживанию

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AIR CONDITIONING IB-11
should be properly Evacuated before recharging with
R e frig eran t-1 2 according to the D I S C H A R G I N G
A D D I N G O IL , E V A C U A T I N G & C H A R G I N G
P R O C E D U R E S FO R C C O T A /C S Y S T E M S .
All service parts are dehydrated and sealed prior to
shipping. They should remain sealed until just prior to
DIAGNOSIS
m aking connections. All parts should be at room
tem perature before uncapping (this prevents condensation
of moisture from the air entering the system). If, for any
reason, caps are removed, but the connections are not made,
parts should be resealed as soon as possible.
TESTING THE REFRIGERANT SYSTEM
If a malfunction in the refrigerant system is suspected
due to abnormal system pressures, check the following:
1. Check outer surfaces of radiator and condenser cores to
be sure they are not plugged with dirt, leaves or other
foreign m aterial. Be sure to check between the
condenser and radiator as well as the outer surfaces.
2. Restrictions or kinks in evaporator core or condenser
core, hoses, tubes, etc.
3. Refrigerant leaks.
4. Check all air ducts for leaks or restrictions. Air
restriction may indicate a plugged (or partially
plugged) evaporator core.
5. Compressor clutch slippage.
6. Improper drive belt tension.
7. Plugged a c c u m u la to r, expansion tube (orifice) or
plugged suction inlet screen (A6 Compressor).
8. Excessive m oisture in re frig e ra n t system. Diagnose
A /C system according to C.C .O.T. System Diagnostic
Procedure (C harts 1 B-4 and 1 B-5).
LEAK TESTING THE REFRIGERANT SYSTEM
Liquid Leak Detectors
There are a num ber of locations (fittings, valves, etc.)
on the air conditioning system where a liquid leak detector
solution may be used to pinpoint refrigerant leaks.
By applying test solution to the area in question with
the swab th at is attached to the bottle cap, bubbles will form
within seconds if there is a leak.
For restricted access areas, such as sections of the
evaporator and condenser, a Leak Detector such as J-6084
or equivalent is more practical for determining and locating
leaks.
J -6 0 8 4 Leak Detector
Tool J-6084 is a propane gas-burning torch which is
used to locate a leak in any part of the system. Refrigerant
gas drawn into the sampling tube attached to the torch will
cause the torch flame to change color in proportion to the
size of the leak. Propane gas fuel cylinders used with the
torch are readily available commercially throughout the
country.
C A U TIO N : Do not use a lig h ted detector in an y
place w h e re com bustible or explosive gases, dusts
or vapors m ay be present.
O p e ra tin g Detector
1. Determine if there is sufficient refrigerant in the system
for leak testing.
2. Open control valve only until a low hiss of gas is heard,
then light gas at opening in chimney.
3. Adjust flame until desired volume is obtained. This is
most satisfactory when blue flame is approximately 3/8
in. above reactor plate. The reaction plate will quickly
heat to a cherry red.
4. Explore for leaks by moving the end of the sampling
hose around possible leak points in the system. Do not
pinch or kink hose.
Since R e frig e ra n t-12 is heavier than air, it is good
practice to place open end of sam pling tube
immediately below point being tested, particularly in
cases of small leaks.
C A U TIO N : Do not b reath e th e fum es th a t are
produced by th e b urning of R e frig e ra n t-12 gas in
the detector fla m e , since such fu m es can be toxic
in large concentrations.
5. W atch for color changes. The color of the flame which
passes through the reaction plate will change to green
or yellow-green when sampling hose draws in very
small leaks of R efrigerant-12. L arge leaks will be
indicated by a change in color to a brilliant blue or
purple; when the sampling hose passes the leaks, the
flame will clear to an almost colorless pale-blue again.
Observations are best made in a semi-darkened area. If
the flame remains yellow when unit is removed from
leak, insufficient air is being drawn in or the reaction
plate is dirty.
A refrigerant leak in the high pressure side of the
system may be more easily detected if the system is
operated for a few minutes, then shut off and checked
im mediately (before system pressures equalize). A leak
on the low pressure side may be more easily detected
after the engine has been shut off for several minutes
(system pressures equalized); this applies particularly
to the front seal.
PRESSURE C Y C L IN G CCOT SYSTEM
C 6 0 , C-K an d G MODELS
C om pressor clutch cycling on C - K & G Series C60
C C O T A /C Systems is accomplished through the use of a
pressure sensing switch, (Refer to Fig. IB-21 &1B-22)
located near the top of the a c c u m u la to r. T h e switch
performs two functions in the system. In addition to cycling
the compressor on and off to control refrigerant flow, the
switch shuts off the compressor clutch when pressure falls to
a predetermined level, indicating low refrigerant charge in
the system.
W hen diagnosis (R e fe r to C h a r t IB-3 & 1 B-4)
indicates replacement of the switch is necessary, it should be
noted that it will not normally be necessary to discharge the
A / C system, as the pressure switch fitting on the
accumulator is equipped with a schrader type valve.
When replacing the pressure cycling switch, a new
oiled " O " ring must be installed and the switch must be
torqued to 10 N-m (7.5 ft lb). Do not exceed this torque, as
the threads in the accum ulator may be stripped.