B3933

CIRCUIT DESCRIPTION
The HVAC control module monitors the temperature of the refrigerant through the evaporator via a evaporator temperature sensor. When the refrigerant temperature is low the sensor resistance and the signal voltage are high. When the refrigerant temperature is high the sensor resistance and the signal voltage are low. The sensor works in conjunction with a switch to meter the flow of refrigerant therefore preventing the freezing of moisture that condenses on the evaporator. An evaporator with too little refrigerant will starve causing insufficient cooling. An evaporator flooded with refrigerant will also cause poor cooling when there is too much liquid refrigerant that cannot vaporize quickly.

CONDITIONS FOR RUNNING THE DTC
The ignition is turned ON.

CONDITIONS FOR SETTING THE DTC
The HVAC control module detects the signal circuit is less than 5 counts (0.09 V).

ACTION TAKEN WHEN THE DTC SETS
^ The HVAC control module will store the trouble code in memory.
^ A default value will be used for the sensor data by the HVAC control module to allow the A/C system to operate.

CONDITIONS FOR CLEARING THE DTC
^ The DTC will become history if the HVAC control module no longer detects a failure.
^ The history DTC will clear after 50 fault free ignition cycles.
^ The DTC can be cleared with a scan tool.

DIAGNOSTIC AIDS
If the condition is not present, refer to Testing for Intermittent and Poor Connections in Diagnostic Aids.

TEST DESCRIPTION

Steps 1-3:

Steps 4-12:

The numbers below refer to the step numbers on the diagnostic table.
3. Tests for the proper operation of the circuit in the high voltage range.
4. Tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to voltage.