Maintaining Chemical Stability; Refrigerant System Diagnosis; Insufficient Cooling "Quick-Check" Procedure; System Performance Test - GMC G Service Manual

IB -10 AIR CONDITIONING
• Replace the seal when a connection has been bro­
ken. When replacing the seal, first dip it in clean 525
viscosity refrigeration oil.
• When making steel-to-aluminum connections, use
the torque for aluminum tubing. (Refer to figure 10.)
MAINTAINING CHEMICAL
STABILITY
The efficient operation of the air conditioning refrigera­
tion system is dependent upon the chemical stability of
Refrigerant-12.
Foreign matter can change the stability of Refrigerant-
12, causing corrosion and wear. Do the following:
1. Before disconnecting a refrigerant connection,
remove dirt or oil at and near the connection. Cap or
plug both sides of the connection.

REFRIGERANT SYSTEM DIAGNOSIS

NOTICE: When performing air conditioning
diagnosis on vehicles equipped with a catalytic
converter, warm the engine to a normal operat­
ing temperature before attempting to Idle the
engine for periods greater than five minutes.
INSUFFICIENT COOLING
"QUICK-CHECK" PROCEDURE
Use the following "hand-feel" procedure if the system
has the proper charge of Refrigerant-12 (providing ambient
temperature is above 21°C (70°F).
1. Engine must be warm and at normal idle speed.
2. Hood and body doors open.
3. Selector (mode) lever set at NORM.
4. Temperature lever at COLD.
5. Blower on HI.
. With compressor engaged, "hand-feel" the tempera­
6
ture of the accumulator and the evaporator inlet pipe
downstream of the orifice.
— BOTH THE SAME TEMPERATURE AND SOME
DEGREE COOLER THAN AMBIENT - Proper condi­
tion: check for other problems (refer to A/C System
Diagnostic Procedure).
— INLET PIPE COOLER THAN ACCUMULATOR SUR­
FACE indicates a low refrigerant charge.
• Add amounts 0.113 kg (4 oz.) of refrigerant
UNTIL BOTH feel the same temperature. Allow
stabilization time between additions.
• Then add one 0.397 kg (0.88 lbs.) can addi­
tional refrigerant. The 0.397 kg/14 oz. dispos­
able can of Refrigerant-12 is the equivalent to
lbs.
0.88

SYSTEM PERFORMANCE TEST

Tool Required:
J 21213-A Four Jack-Dual Range Temperature
Tester
1. Open doors or windows.
2. Keep tools clean and dry.
3. When adding 525 viscosity refrigerant oil (refer to
ADDING OIL in the Discharging, Evacuating, Adding
Oil and Charging Procedures for CCOT A/C sys­
tems), the transfer device and container should be
clean and dry.
4. Have everything ready before opening a line. Do not
leave the A/C system open longer than necessary.
5. After opening, evacuate before recharging with
Refrigerant-12 according to "Discharging, Evacuat­
ing, Adding Oil, Charging and Discharging the Sys­
tem" procedures.
. Sen/ice parts are dehydrated and sealed before ship­
6
ping. Open just before making connections. Keep at
room temperature before uncapping (this prevents
moisture from entering the system). If the connec­
tions are not made, reseal the parts.
2. Position the right lever in the "NORM" mode.
3. Place the left lever in the cold (blue) position.
4. Place the blower switch at "HI."
5. Install J 21213-A at the instrument panel right outlet
(figure ).
1 1
. Start the engine and run at 2000 rpm.
6
7. After one minute, the minimum drop in temperature
from the right outlet should be:
Condenser Inlet 21 °C
Temperature (70°F)
Instrument Panel 11°C
(20°F)
Right Outlet
Temperature
(Minimum Drop)
27°C 32-44°C
(80°F) (90-110°F)
14°C 17°C
(25°F) (30°F)
G M T B -0 959-1L