Jeep cherokee 2000 Service Manual page 1476

24 - 12 HEATING AND AIR CONDITIONING
DIAGNOSIS AND TESTING (Continued)
Condition
The low side pressure is
normal or slightly high, and
the high side pressure is too
high.
The low side pressure is too
high, and the high side
pressure is too low.
The low side pressure is too
low, and the high side
pressure is too high.
BLOWER MOTOR
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, REFER TO GROUP 8M - PASSIVE RESTRAINT
SYSTEMS BEFORE ATTEMPTING ANY STEERING
WHEEL, STEERING COLUMN, OR INSTRUMENT
PANEL COMPONENT DIAGNOSIS OR SERVICE. FAIL-
URE TO TAKE THE PROPER PRECAUTIONS COULD
RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT
AND POSSIBLE PERSONAL INJURY.
For circuit descriptions and diagrams, refer to
8W-42 - Air Conditioning/Heater in Group 8W - Wir-
ing Diagrams. Possible causes of an inoperative
blower motor include:
Pressure Diagnosis
Possible Causes
1. Condenser air flow
restricted.
2. Inoperative cooling fan.
3. Refrigerant system
overcharged.
4. Air in the refrigerant
system.
5. Engine overheating.
1. Accessory drive belt
slipping.
2. Fixed orifice tube not
installed.
3. Faulty compressor.
1. Restricted refrigerant flow
through the refrigerant lines.
2. Restricted refrigerant flow
through the fixed orifice tube.
3. Restricted refrigerant flow
through the condenser.
1. Check the condenser for damaged fins, foreign
objects obstructing air flow through the condenser
fins, and missing or improperly installed air seals.
Refer to Group 7 - Cooling System for more
information on air seals. Clean, repair, or replace
components as required.
2. Refer to Group 7 - Cooling System for more
information. Test the cooling fan and replace, if
required.
3. See Refrigerant System Charge in this group.
Recover the refrigerant from the refrigerant
system. Charge the refrigerant system to the
proper level, if required.
4. See Refrigerant System Leaks in this group.
Test the refrigerant system for leaks. Repair,
evacuate and charge the refrigerant system, if
required.
5. Refer to Group 7 - Cooling System for more
information. Test the cooling system and repair, if
required.
1. Refer to Group 7 - Cooling System for more
information. Inspect the accessory drive belt
condition and tension. Tighten or replace the
accessory drive belt, if required.
2. See Fixed Orifice Tube in this group. Install the
missing fixed orifice tube, if required.
3. See Compressor in this group. Replace the
compressor, if required.
1. See Liquid Line and Suction and Discharge
Line in this group. Inspect the refrigerant lines for
kinks, tight bends or improper routing. Correct the
routing or replace the refrigerant line, if required.
2. See Fixed Orifice Tube in this group. Replace
the restricted fixed orifice tube, if required.
3. See Condenser in this group. Replace the
restricted condenser, if required.
• Faulty fuse
• Faulty blower motor circuit wiring or wire har-
ness connectors
• Faulty blower motor resistor
• Faulty blower motor relay
• Faulty blower motor switch
• Faulty heater-A/C mode control switch
• Faulty blower motor.
Possible causes of the blower motor not operating
in all speeds include:
• Faulty fuse
• Faulty blower motor switch
• Faulty blower motor resistor
• Faulty blower motor circuit wiring or wire har-
ness connectors.
Correction
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