BLOWER MOTOR AND WHEEL ASSEMBLY
VIBRATION AND/OR NOISE DIAGNOSIS
The blower speed switch, in conjunction with the
resistor block, supplies the blower motor with varied
voltage.
CAUTION: Stay clear of the blower motor and resis-
tor block (Hot). Do not operate the blower motor
with the resistor block removed from the heater A/C
housing.
Refer to the Blower Motor Vibration/Noise chart in
this section for diagnosis.
COMPRESSOR NOISE DIAGNOSIS
Excessive noise while the A/C is being used, can be
caused by loose mounts, clutch, or high operating
pressure. Verify compressor drive belt condition,
proper refrigerant charge and head pressure before
compressor repair is performed.
COMPRESSOR CLUTCH/COIL
The air conditioning compressor clutch electrical
circuit is controlled by the Powertrain Control Mod-ule. It is located in the engine compartment outboard
of the battery.
If the compressor clutch does not engage verify
refrigerant charge.
If the compressor clutch still does not engage check
for battery voltage at the pressure transducer located
on the liquid line. If voltage is not detected, refer to:
²Group 8W, Wiring diagrams.
²Powertrain Diagnostic Procedures manual for
diagnostic information.
If voltage is detected at the pressure transducer,
connect pressure transducer and check for battery
voltage between the compressor clutch connector ter-
minals.
If voltage is detected, perform A/C Clutch Coil
Tests.
TESTS
(1) Verify battery state of charge. (Test indicator in
battery should be green).
(2) Connect an ampmeter (0-10 ampere scale) in
series with the clutch coil terminal. Use a voltmeter
(0-20 volt scale) with clip leads measuring voltage
across the battery and A/C clutch.
(3) With A/C control in A/C mode and blower at
low speed, start the engine and run at normal idle.
(4) The A/C clutch should engage immediately and
the clutch voltage should be within two volts of the
battery voltage. If the A/C clutch does not engage,
test the fuse.
(5) The A/C clutch coil is acceptable if the current
draw is 2.0 to 3.7 amperes at 11.5-12.5 volts at clutch
coil. This is with the work area temperature at 21ÉC
(70ÉF). If voltage is more than 12.5 volts, add electri-
cal loads by turning on electrical accessories until
voltage reads below 12.5 volts.
Fig. 7 A/C PERFORMANCE TEMPERATURES
VOLTAGE CONDITION
0 Transducer faulty or no voltage
from PCM
.150 to .450 Transducer good/Low Pressure
Cutout condition
.451 to 4.519 Normal operating condition
4.520 to 4.850 Transducer good/High
Pressure Cutout condition
5 Transducer faulty
24 - 12 HEATING AND AIR CONDITIONINGNS/GS
DIAGNOSIS AND TESTING (Continued)
