(4) With the A/C compressor clutch engaged, duct
temperature should not be less than 2° C (35° F) or
more than 12° C (54° F). The compressor clutch may
cycle, depending upon the ambient temperature and
humidity. If the clutch cycles, use the readings
obtained before the clutch disengaged.
(5) If the A/C compressor clutch has not cycled off
and the duct temperature is less than 2° C (35° F),
check the evaporator temperature sensor and circuit
by performing the ATC Function Test (Refer to 24 -
HEATING & AIR CONDITIONING - DIAGNOSIS
AND TESTING - ATC FUNCTION TEST).
(6) If the air outlet temperature fails to meet the
specifications, refer to the A/C System Diagnosis
chart.
A/C SYSTEM DIAGNOSIS
Condition
Possible Causes
Correction
Rapid A/C compressor clutch
cycling (ten or more cycles
per minute).
Very low refrigerant system
charge.
See Refrigerant System Leaks in this group.
Test the refrigerant system for leaks. Repair,
evacuate and charge the refrigerant system, if
required.
Equal pressures, but the
compressor clutch does not
engage.
1. No refrigerant in the refrig-
erant system.
1. See Refrigerant System Leaks in this
group. Test the refrigerant system for leaks.
Repair, evacuate and charge the refrigerant
system, if required.
2. Faulty fuse.
2. Check the fuses in the Power distribution
block and junction block. Repair the shorted
circuit or component and replace the fuses, if
required. Refer to Group 8.
3. Faulty A/C compressor
clutch coil.
3. See A/C Compressor Clutch Coil in this
group. Test the compressor clutch coil and
replace, if required.
4. Improperly installed or faulty
evaporator temperature sensor.
4. See Evaporator Temperature Sensor in this
group. Test the sensor and replace, if re-
quired.
5. Faulty A/C pressure trans-
ducer.
5. See A/C Pressure Transducer in this
group. Test the sensor and replace, if re-
quired.
6. Faulty engine Control Mod-
ule (ECM).
6. Refer to Group 9 - Engine Electrical Diag-
nostics for testing of the ECM. Test the ECM
and replace, if required.
Normal pressures, but A/C
Performance Test air temper-
atures at center panel outlet
are too high.
1. Excessive refrigerant oil in
system.
1. See Refrigerant Oil Level in this group.
Recover the refrigerant from the refrigerant
system and inspect the refrigerant oil content.
Restore the refrigerant oil to the proper level,
if required.
2. Blend door cable improperly
installed or faulty.
2. See Mode Door Cables in this group. In-
spect the cable for proper operation and re-
place, if required.
3. Blend-air door(s) inoperative
or sealing improperly.
3. See HVAC Housing in this group. Inspect
the blend-air door(s) for proper operation and
sealing. Repair if required.
24 - 4
HEATING & AIR CONDITIONING
VA
