Jeep Cherokee (XJ): Blower motor switch. Compressor. Compressor clutch coil
For circuit descriptions and diagrams, refer to
8W-42 - Air Conditioning/Heater in Group 8W - Wiring
Diagrams.
WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS,
REFER TO GROUP 8M - PASSIVE
RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY
STEERING WHEEL, STEERING COLUMN, OR
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRECAUTIONS
COULD RESULT IN ACCIDENTAL AIRBAG
DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Check for battery voltage at the fuse in the
Power Distribution Center (PDC). If OK, go to Step
2. If not OK, repair the shorted circuit or component
as required and replace the faulty fuse.
(2) Turn the ignition switch to the Off position.
Disconnect and isolate the battery negative cable.
Remove the heater-A/C control from the instrument
panel. Check for continuity between the ground circuit
cavity of the heater-A/C control wire harness
connector and a good ground. There should be continuity.
If OK, go to Step 3. If not OK, repair the open
circuit to ground as required.
(3) With the heater-A/C control wire harness connector
unplugged, place the heater-A/C mode control
switch knob in any position except the Off position.
Check for continuity between the ground circuit terminal
and each of the blower motor driver circuit terminals
of the heater-A/C control as you move the
blower motor switch knob to each of the four speed
positions. There should be continuity at each driver
circuit terminal in only one blower motor switch
speed position. If OK, test and repair the blower
driver circuits between the heater-A/C control connector
and the blower motor resistor as required. If
not OK, replace the faulty heater-A/C control unit. When investigating an air conditioning related
noise, you must first know the conditions under
which the noise occurs. These conditions include:
weather, vehicle speed, transmission in gear or neutral,
engine speed, engine temperature, and any
other special conditions. Noises that develop during
air conditioning operation can often be misleading.
For example: What sounds like a failed front bearing
or connecting rod, may be caused by loose bolts, nuts,
mounting brackets, or a loose compressor clutch
assembly.
Drive belts are speed sensitive. At different engine
speeds and depending upon belt tension, belts can
develop noises that are mistaken for a compressor
noise. Improper belt tension can cause a misleading
noise when the compressor clutch is engaged, which
may not occur when the compressor clutch is disengaged.
Check the serpentine drive belt condition and
tension as described in Group 7 - Cooling System
before beginning this procedure.
(1) Select a quiet area for testing. Duplicate the
complaint conditions as much as possible. Switch the
compressor on and off several times to clearly identify
the compressor noise. Listen to the compressor
while the clutch is engaged and disengaged. Probe
the compressor with an engine stethoscope or a long
screwdriver with the handle held to your ear to better
localize the source of the noise.
(2) Loosen all of the compressor mounting hardware
and retighten. Tighten the compressor clutch
mounting nut. Be certain that the clutch coil is
mounted securely to the compressor, and that the
clutch plate and pulley are properly aligned and have
the correct air gap. See Compressor and Compressor
Clutch in the Removal and Installation section of this
group for the procedures.
(3) To duplicate a high-ambient temperature condition
(high head pressure), restrict the air flow
through the condenser. Install a manifold gauge set exceed 2760 kPa (400 psi).
(4) Check the refrigerant system plumbing for
incorrect routing, rubbing or interference, which can
cause unusual noises. Also check the refrigerant lines
for kinks or sharp bends that will restrict refrigerant
flow, which can cause noises. See Suction and Discharge
Line in the Removal and Installation section
of this group for more information.
(5) If the noise is from opening and closing of the
high pressure relief valve, evacuate and recharge the
refrigerant system. See Refrigerant System Evacuate
and Refrigerant System Charge in the Service Procedures
section of this group. If the high pressure relief
valve still does not seat properly, replace the compressor.
(6) If the noise is from liquid slugging on the suction
line, replace the accumulator. See Accumulator
in the Removal and Installation section of this group
for the procedures. Check the refrigerant oil level
and the refrigerant system charge. See Refrigerant
Oil Level and Refrigerant System Charge in the Service
Procedures section of this group. If the liquid
slugging condition continues following accumulator
replacement, replace the compressor.
(7) If the noise continues, replace the compressor
and repeat Step 1. For circuit descriptions and diagrams, refer to
8W-42 - Air Conditioning/Heater in Group 8W - Wiring
Diagrams. The battery must be fully-charged
before performing the following tests. Refer to Group
8A - Battery for more information.
(1) Connect an ammeter (0 to 10 ampere scale) in
series with the clutch coil terminal. Use a voltmeter
(0 to 20 volt scale) with clip-type leads for measuring
the voltage across the battery and the compressor
clutch coil.
(2) With the heater-A/C mode control switch in any
A/C mode, and the blower motor switch in the lowest
speed position, start the engine and run it at normal
idle.
(3) The compressor clutch coil voltage should read
within two volts of the battery voltage. If there is
voltage at the clutch coil, but the reading is not
within two volts of the battery voltage, test the
clutch coil feed circuit for excessive voltage drop and
repair as required. If there is no voltage reading at
the clutch coil, use a DRB scan tool and the proper
Diagnostic Procedures manual for testing of the compressor
clutch circuit. The following components
must be checked and repaired as required before you
can complete testing of the clutch coil: (4) The compressor clutch coil is acceptable if the
current draw measured at the clutch coil is 2.0 to 3.9
amperes with the electrical system voltage at 11.5 to
12.5 volts. This should only be checked with the work
area temperature at 21 C (70 F). If system voltage
is more than 12.5 volts, add electrical loads by turning
on electrical accessories until the system voltage
drops below 12.5 volts.
(a) If the clutch coil current reading is four
amperes or more, the coil is shorted and should be
replaced.
(b) If the clutch coil current reading is zero, the
coil is open and should be replaced.Blower motor switch
Compressor
Compressor clutch coil
Blower motor. Blower motor relay. Blower motor resistor
Other materials:
Vehicle security alarm
The Vehicle Security Alarm monitors the vehicle doors
for unauthorized entry and the Keyless Enter-N-Go
Start/Stop button for unauthorized operation. While the
Vehicle Security Alarm is armed, interior switches for
door locks and liftgate release are disabled.
If something triggers the alarm, ...