Jeep Cherokee 2000 Service Manual - page 1872
Pressure Diagnosis
Condition
Possible Causes
Correction
Rapid compressor clutch
cycling (ten or more cycles
per minute).
1. Low refrigerant system
charge.
1. 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
refrigerant system.
2. Faulty fuse.
3. Faulty compressor clutch
coil.
4. Faulty compressor clutch
relay.
5. Improperly installed or
faulty low pressure cycling
clutch switch.
6. Faulty high pressure
cut-off switch.
7. Faulty Powertrain Control
Module (PCM).
1. See Refrigerant System Leaks in this group.
Test the refrigerant system for leaks. Repair,
evacuate and charge the refrigerant system, if
required.
2. Check the fuses in the Power Distribution
Center and the junction block. Repair the shorted
circuit or component and replace the fuses, if
required.
3. See Compressor Clutch Coil in this group. Test
the compressor clutch coil and replace, if
required.
4. See Compressor Clutch Relay in this group.
Test the compressor clutch relay and relay
circuits. Repair the circuits or replace the relay, if
required.
5. See Low Pressure Cycling Clutch Switch in
this group. Test the low pressure cycling clutch
switch and tighten or replace, if required.
6. See High Pressure Cut-Off Switch in this
group. Test the high pressure cut-off switch and
replace, if required.
7. Refer to the proper Diagnostic Procedures
manual for testing of the PCM. Test the PCM and
replace, if required.
Normal pressures, but A/C
Performance Test air
temperatures at center panel
outlet are too high.
1. Excessive refrigerant oil in
system.
2. Blend-Air door inoperative
or sealing improperly.
3. Blend-Air door motor faulty
or inoperative.
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. See Blend-Air Door under Heater-A/C Housing
Door in this group. Inspect the blend-air door for
proper operation and sealing and correct, if
required.
3. Perform Blend-Air door motor diagnosis,
replace if faulty.
The low side pressure is
normal or slightly low, and
the high side pressure is too
low.
1. Low refrigerant system
charge.
2. Refrigerant flow through
the accumulator is restricted.
3. Refrigerant flow through
the evaporator coil is
restricted.
4. Faulty compressor.
1. See Refrigerant System Leaks in this group.
Test the refrigerant system for leaks. Repair,
evacuate and charge the refrigerant system, if
required.
2. See Accumulator in this group. Replace the
restricted accumulator, if required.
3. See Evaporator Coil in this group. Replace the
restricted evaporator coil, if required.
4. See Compressor in this group. Replace the
compressor, if required.
XJ
HEATING AND AIR CONDITIONING
24 - 11
DIAGNOSIS AND TESTING (Continued)