Grand Caravan FWD V6-3.0L VIN 3 (1999)
Resistance Measurement Table
The evaporator probe is located in the unit housing and placed in the evaporator fins. The probe prevents evaporator freeze-up. This is done by cycling
the compressor clutch OFF when evaporator temperature drops below freeze point. It cycles ON when the evaporator temperature rises above freeze
point. The evaporator probe uses a thermistor probe in a capillary tube. The tube is inserted between the evaporator fins in the heater-A/C unit housing.
A malfunctioning evaporator probe may show symptoms such as:
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Ice blocking the airflow, or frost exiting out of the outlets and vents
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No air conditioning operation
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No power to the compressor clutch during A/C selection
The work area and vehicle must be between 16° C (60° F) and 32° C (90° F) during testing.
1. Place the vehicle in a location out of direct sunlight and allow the vehicle to come to ambient temperature (the engine can remain warm).
2. With the engine OFF, lower the windows, and turn on the interior blower (with the system in Fresh Air mode).
3. Place a thermometer in one of the Instrument Panel outlets, and a second one in the intake duct (plenum area by the windshield wipers).
4. Allow the blower to run until both temperatures readings are within 2° F of one another and constant.
5. Remove the electrical connector from the evaporator probe and measure the resistance of the probe with a multimeter.
6. Consult the temperature/resistance chart and table to determine whether the resistance is within specification.
