Blower Motor Resistor; Blower Motor Switch; Compressor - Jeep Wrangler 1999 Electronic Service Manual

TJ
DIAGNOSIS AND TESTING (Continued)
between the cavity for relay terminal 86 and the high
blower motor relay control circuit cavity of the blower
motor switch wire harness connector at all times. If
OK, go to Step 5. If not OK, repair the open circuit
as required.
(5) The coil ground terminal cavity (85) is con-
nected to ground. This terminal supplies the ground
for the relay electromagnet coil. There should be con-
tinuity between the cavity for relay terminal 85 and
a good ground at all times. If not OK, repair the open
circuit as required.

BLOWER MOTOR RESISTOR

For circuit descriptions and diagrams, refer to
8W-42 - Air Conditioning/Heater in Group 8W - Wir-
ing Diagrams.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, REFER TO
RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY
STEERING WHEEL,
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
(1) Disconnect and isolate the battery negative
cable.
(2) Remove the kick cover from the heater-A/C
housing and unplug the wire harness connector from
the blower motor resistor.
(3) Check for continuity between each of the
blower motor switch input terminals of the resistor
and the resistor output terminal. In each case there
should be continuity. If OK, repair the wire harness
circuits between the blower motor switch and the
blower motor resistor or blower motor relay as
required. If not OK, replace the faulty blower motor
resistor.

BLOWER MOTOR SWITCH

For circuit descriptions and diagrams, refer to
8W-42 - Air Conditioning/Heater in Group 8W - Wir-
ing Diagrams.
WARNING: ON VEHICLES EQUIPPED WITH AIR-
BAGS, REFER TO
RESTRAINT SYSTEMS BEFORE ATTEMPTING ANY
STEERING WHEEL,
INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRE-
CAUTIONS COULD RESULT IN ACCIDENTAL AIR-
BAG DEPLOYMENT AND POSSIBLE PERSONAL
INJURY.
GROUP 8M - PASSIVE
STEERING COLUMN,
GROUP 8M - PASSIVE
STEERING COLUMN,
HEATING AND AIR CONDITIONING
(1) Turn the ignition switch to the On position and
check for battery voltage at the fuse in the fuseblock
module. 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, but do not unplug the wire harness connec-
tors. Connect the battery negative cable. Turn the
ignition switch to the On position. Check for battery
voltage at the fused ignition switch output (run) cir-
cuit cavity of the heater-A/C mode control switch
wire harness connector. If OK, go to Step 3. If not
OK, repair the open circuit to the fuseblock module
as required.
(3) Select any one of the heater-A/C mode control
positions except Off to turn the system on. Check for
battery voltage at the low blower motor driver circuit
cavity of the heater-A/C mode control switch wire
OR
harness connector. If OK, go to Step 4. If not OK,
replace the faulty heater-A/C mode control switch.
(4) Check for battery voltage at the low blower
motor driver circuit cavity of the blower motor switch
wire harness connector. If OK, go to Step 5. If not
OK, repair the open circuit to the heater-A/C mode
control switch wire harness connector as required.
(5) Check for battery voltage at each of the
remaining blower motor switch wire harness connec-
tor cavities as you move the switch to each blower
motor speed position. Voltage should be present in
each cavity at only one switch position. If OK, see
the diagnosis for the blower motor resistor and/or the
blower motor relay in this group. If not OK, replace
the faulty blower motor switch.

COMPRESSOR

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 neu-
tral, 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
OR
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 disen-
gaged. Check the serpentine drive belt condition and
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