(4) With th e A/C compr essor clutch en gaged, duct
temper ature should not be less tha n 2° C (35° F) or
more tha n 12° C (54° F). The com pr essor clut ch ma y
cycle, depen ding upon t he ambient t empera ture and
humidity. If th e clutch cycles, use the readings
obtained before the clu tch disengaged.
(5) If the A/C compr essor clutch has not cycled off
and the duct temper ature is less than 2° C (35° F),
check th e eva por ator temper ature sensor and circu it
by per formin g the ATC Function Test (Refer to 24 -
HEATING & AIR CONDITIONING - DIAGNOSIS
AND TESTING - ATC F UNCTION TE ST).
(6) If t he air outlet temper atur e fails to meet the
specifica tions, refer to th e A/C System Diagn osis
chart.
A/C SY ST EM DI AGNOSI S
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
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