Chrysler Conquest 1988 Service Manual page 953

AIR CONDITIONING - Service Adiustment Procedures
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To Test the High Pressure Switch (Engine Off)
(1) Jump the wire leads.
(2) Press the A/C switch and blower switch ON.
(3) Momentarily turn the ignition switch on (do not crank the
engine), and listen for the clutch engaging.
(4) If the clutch does not engage, the thermistor, low pressure
switch, coolant temperature switch, or fuse may be faulty.
Correct fault.
(5) If clutch engages, connect the manifold gauge set and read
pressure. At any pressure of 2,010 kPa (291.5 psi), the
switch must be off.
(6) If the clutch does not engage, replace -the switch.
THERMISTOR
The thermistor turns on/off the compressor clutch depending
on the temperature of the air flowing through the evaporator
outlet.
When the air temperature at the evaporator outlet rises due to
reduced air flow rate, clogged evaporator fin or insufficient
refrigerant, the thermistor detects it and sends the signal to the
automatic air conditioner to turn on the compressor clutch.
If the evaporator fin surface is covered with frost, the faulty
thermistor is suspected.
To Test the Thermistor
(1) Disconnect the thermistor connector at the evaporator case
and measure the resistance with an ohmmeter. If the
resistance value is within the range shown in the illustra-
tion, the thermistor is in order. If not, replace the thermis-
tor.
(2) If the thermistor is in order, the automatic air conditioner
may be faulty. Replace it.
ENGINE COOLANT TEMPERATURE SW1TCl-i
The engine coolant temperature switch is located on the
thermostat housing, and is connected to the clutch in series.
When the coolant temperature in the radiator reaches above
113°C (235"F), it turns the compressor OFF. This is to prevent
engine overheating.
To Test the Engine Coolant Temperature Switch
(1) Remove wire from engine coolant temperature switch and
jump leads together.
(2) Press the A/C switch and blower switch ON.
(3) Momentarily turn the ignition switch ON (do not crank the
engine), and listen for the clutch engaging.
(4) If the clutch does not engage the thermistor, low pressure
switch, high pressure switch wiring or fuse may be faulty.
(5) If clutch engage, replace the switch.