HEATING
AND
AIR
CONDITIONING
24 -
TEMPERATURE
IN
TEST AREA
21-29° C
(70-85°
F)
VERIFY R-12 CHARGE-CONNECT MANIFOLD GAUGES
SEE
MAINTENANCE AND ADJUSTMENTS SECTION
IF
R-12
CHARGE
IS
LOW, CORRECT LEAK, EVACUATE, AND CHARGE SYSTEM
BYPASS
CYCLING CLUTCH SWITCH USING JUMPER WIRE REFER
TO
GROUP
8W,
WIRING DIAGRAMS
START ENGINE ADJUST IDLE
TO 1000
rpm
IN
PARK OR NEUTRAL
WITH
PARK BRAKE SET LOCATE AND REMOVE BOTH
VACUUM LINES AT RECIRC DOOR ACTUATOR INSTALL
LT-GN LINE WHERE DK-GN LINE HAD BEEN
CLOSE
PASSENGER COMPARTMENT
SET
CONTROL TO A/C, PANEL, HIGH BLOWER, FULL HEAT
ENGINE
RPM BLOWER
MOTOR
SPEED
I
EVAPORATOR
I
SUCTION GAUGE
I
PSIG
(kPag)
1
COMPRESSOR
DISCHARGE
GAUGE
PSIG
(kPag)
2
—m
POSSIBLE
I
CAUSE
I
20-35
PSIG
140-240
PSIG
1000 —
HI
(140 TO 240
kPag)
(966
TO
1656
kPag)
i
— NORMAL
Cr a
FREEZE
H-VALVE 15 INCHES
OF VACUUM
THAW
H-VALVE 38 PSIG
(262
kPag)
OR MORE THEN
DROPS
TO 25 TO 35
PSIG
(172
TO
240
kPag)
RETURN RECIRC DOOR VACUUM LINES
TO
NORMAL a
1000
HI
20 30
PSIG
(140 TO 207
kPag)
H240
PSIG OR HIGHER
(1656
kPag)
20-30
PSIG
(140-207
kPag)
140
PSIG
(966
kPag)
OR
LESS
H-VALVE
STUCK OPEN
IF
CONDITIONS
CANNOT BE MET
H-VALVE
STUCK CLOSED
IF
CONDITIONS
CANNOT BE MET
RESTRICTED
CONDENSER-
RESTRICTED
DISCHARGE
LINE
-RADIATOR
OVERHEATING-
AIR
IN
SYSTEM- OVERCHARGED
SYSTEM-COOLING FAN INOP.
RECONNECT LOW PRESSURE/CYCLING SWITCH AND RECONNECT THE VACUUM LINES
TO
THE RECIRC/ACUATOR DEFECTIVE
COMPRESSOR
HEAD
GASKET
OR
DISCHARGE
REEDS
J9124-104
AIR
CONDITIONING REFRIGERANT SYSTEM DIAGNOSIS
24-12
HEATING
AND AIR
CONDITIONING
PERFORMANCE TEMPERATURE CHART
Garage
Ambient
Temperature
21
°C
(70°F) 26.5°C
(80°F) 32°C
(90°F) 3/.5°'J
(100T) 43°C
(110°F)
Discharge
Air Temperature
3-10°C
(38-50°F) 6-12°C
(42-54'F) 8-14°C
(46-58°F) 10-17°C
(50-62°F) 12-19°C
(54-66°F)
Compressor
Discharge Pressure
1344 a
1620 a
1861 kPag 2103 a 1379kPcg
2344 a
Compressor
Discharge Pressure
120 •
195 PS'9 160 .
235 PS'9 200 .
270 PS'9 240 .
305 PS'9 280 .
340 PS'9
Evaporator
Suction Pressure
124 kPag
207 a 138 kPag
241 J 269 kPag III kP°9
296 179 ,D
324 kPag
Evaporator
Suction Pressure
18 .
30 PS'9 20 .
35 pS'g 22
39 pS,g
25 .
43 pS'g 26 .
47 pS'9
J9124-97 pressure must drop to below -50 kPag (15 inch of vacu
um).
If the condition is not met the H-valve is stuck
open and should be replaced. Remove Liquid C02 and
watch evaporator suction pressure; it should increase to a minimum of 262 kPag (38 psig) and then stabilize to a
pressure of 172-240 kPag (25-35 psig). Any H-valve
which does not produce this response is stuck open and should be replaced.
(4) Connect A/C water valve vacuum hose (gray)
and set temperature control in cool position.
(5) Set engine speed at 1,000 RPM and blower on
HI.
The evaporator suction pressure should be in the
range of 138-207 kPag (20-30 psig). If compressor dis charge is higher than 1 656 kPag (240 psig), check
for restricted discharge line, radiator overheating, air in system or faulty viscous fan drive. If discharge
pressure is less than 966 kPag (140 psig), check com
pressor head gaskets and discharge reeds.
(6) Connect the electrical wires to the electronic
temperature cycling clutch switch.
VACUUM CONTROL SYSTEM ADJUSTMENTS
AND TESTS To keep the vacuum harness in place, common vi
nyl tape (sometimes called plastic tape of electri
cian's tape) cannot be used. It will cause the tube to
deteriorate directly under the tape, when high under
hood temperatures are involved. A compatible nylon type of tape such as MS CH69 (#281) or an equivalent must be used.
The test of the push button switch operation deter
mines whether or not the vacuum and electrical cir cuits are properly connected and the controls are
functioning properly. However, it is possible that this system operating perfectly at engine idle during high
manifold vacuum, may not function properly at high engine speeds. Before starting this test, stop engine and make certain the vacuum source hose at engine
intake manifold is tight on its connector.
EXPANSION (H) VALVE TEST
Test must be made at ambient temperature of
21°C-29°C (70°F-85°F).
After performing all previously mentioned tests,
conduct the H-valve test as follows:
(1) Operate the engine at 1,000 RPM with the win
dows closed. Set air conditioning controls for MAX
A/C,
high blower, temperature control lever in full
reheat position and cycling clutch switch electrically
bypassed. Disconnect and plug the water valve vac uum hose in the engine compartment. (2) Operate the system for at least 5 minutes in or
der to obtain partial stabilization and sufficient re
heat to load the system. Pressure at the discharge service port should reach 966-1 656 kPag (140-240
psig) (Fig. 6). If head pressure of 966-1 656 kPag (140-240 psig) cannot be obtained, check system
charge level.
Fig.
6
Expansion
(H)
Valve
Test
WARNING:
EXTREME
CARE
MUST
BE
USED
WHEN
HANDLING
LIQUID
C02 AS
SKIN
INJURY
CAN OC
CUR
IF
PROTECTIVE
GLOVES
ARE NOT
WORN.
(3) Put Liquid C02 on control head (completely cover
head) for a minimum of 30 seconds. Evaporator suction
