Diagnosis; Leak Testing The Refrigerant System - Chevrolet LIGHT DUTY TRUCK (SERIES 10-35) Service Manual

A ND C H A R G IN G PROCEDURES
SYSTEMS are described on following pages in the Service
Manual.
W ith R-12 Drum or 14 oz. Disposable Can
Charging:
• Do not Charge while compressor system is hot.
• ALW AYS CH A R G E T HROUGH LOW-SIDE OF
A /C SYSTEM (low-side fitting is found on Accumulator).
• NEVER CONNECT ON HIGH-SIDE of A /C
system or to any system having a pressure higher than
indicated on the R-12 container.
• When opening valves designed for use with container,
follow manufacturer's directions carefully.
• Always use pressure gages before and during
Charging.
• Empty R-12 container completely before disposing.
• See Disposable Can C H A R G IN G procedures later
in Service Manual.
W ith J-23500-01 Charging Station:
• Follow manufacturer's directions carefully with three
exceptions:
• HI-PRESSURE VALVE OF G A G E SET SHOULD
BE CLOSED AT ALL TIMES D U R IN G CH A R G IN G .
• DO NOT CONNECT H IG H PRESSURE LIN E TO
A /C SYSTEM.
• A LL EVACUATING A N D C H A R G IN G OF A /C
SYSTEM MUST BE PERFORM ED THROUGH LOW

LEAK TESTING THE REFRIGERANT SYSTEM

Whenever a refrigerant leak is suspected in the system
or a service operation performed which results in disturbing
lines or connections, it is advisable to test for leaks.
Common sense should be the governing factor in
performing any leak test, since the necessity and extent of
any such test will, in general, depend upon the nature of the
complaint and the type of service performed on the system.
J -6 0 8 4 Leak D etector
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.
CAUTION: Do not use lighted detector in
any place where combustible or explosive
gases, dusts or vapors may be present.
O perating D etector
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
FOR C.C.O.T.
PRESSURE VALVE/LINE TO LOW-SIDE SERVICE
FITTING ON ACCUMULATOR.
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 material. 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 accumulator, expansion tube (orifice) or
compressor suction inlet screen.
8. Excessive moisture in refrigerant system.
9. Start properly operating, tuned engine and set up
A /C system according to appropriate PERFORM ANCE
CONDITIONS stated in C.C.O.T. System Diagnostic
Procedure (Fig. IB-17 & Chart IB-4).

DIAGNOSIS

is most satisfactory when blue flame is approximately 3/8"
above reactor plate. The reaction plate will quickly heat to
a cherry red.
4.
hose around possible leak points in the system. Do not pinch
or kink hose.
NOTICE:
practice to place open end of sampling
immediately below point being tested, particularly in
cases of small leaks.
CAUTION: Do not breathe the fumes that
are produced by the burning of R-12 gas
in the detector flame, since such fumes
can be toxic in large concentrations.
5.
which passes through the reaction plate will change to green
or yellow-green when sampling hose draws in very small
leaks of R-12. Large 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.
AIR CO NDITIO NING
Explore for leaks by moving the end of the sampling
Since R-12 is heavier than air, it is good
Watch for color changes. The color of the flame
IB -1 3
tube
LIGHT T R U C K S ER V IC E MANU