Chrysler 1998 Voyager Service Manual page 1829

NS
DIAGNOSIS AND TESTING (Continued)
A/C PRESSURE TRANSDUCER VOLTAGE
VOLTAGE
0
.150 TO .450
.451 TO 4.519
4.520 TO 4.850
5
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, loose clutch, or high operat-
ing pressure. Verify compressor drive belt condition,
proper refrigerant charge and head pressure before
compressor repair is performed.
If the A/C drive belt slips at initial start-up, it does
not necessarily mean the compressor has failed.
With the close tolerances of a compressor it is pos-
sible to experience a temporary lockup. The longer
the A/C system is inactive, the more likely the condi-
tion to occur.
This condition is the result of normal refrigerant
movement within the A/C system caused by temper-
ature changes. The refrigerant movement may wash
the oil out of the compressor.
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.
CONDITION
TRANSDUCER FAULTY
OR NO VOLTAGE FROM
PCM
TRANSDUCER
GOOD/LOW PRESSURE
CUTOUT CONDITION
NORMAL OPERATING
CONDITION
TRANSDUCER
GOOD/HIGH
PRESSURE CUTOUT
CONDITION
TRANSDUCER FAULTY
HEATING AND AIR CONDITIONING
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:
• Group 8W, Wiring diagrams.
• Powertrain 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 21°C
(70°F). If voltage is more than 12.5 volts, add electri-
cal loads by turning on electrical accessories until
voltage reads below 12.5 volts.
(6) If coil current reads zero, the coil is open and
should be replaced. If the ammeter reading is 4
amperes or more, the coil is shorted and should be
replaced. If the coil voltage is not within two volts of
the battery voltage, test clutch coil feed circuit for
excessive voltage drop.
EXPANSION VALVE
NOTE: Special effort must be used to keep all
R-134a system components moisture-free. Moisture
in the oil is very difficult to remove and will cause a
reliability problem with the compressor.
TESTS
NOTE: Expansion valve tests should be performed
after compressor tests.
Review Safety Precautions and Warnings in this
group. The work area and vehicle temperature must
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