B3933

DTC B3933

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview






Circuit Description

The HVAC control module monitors the temperature of the refrigerant through the evaporator via an 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.

DTC Descriptors

This diagnostic procedure supports the following DTC:

B3933 Air Conditioning (A/C) Evaporator Temperature Sensor Circuit

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 volt).

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 Conditions and Poor Connections in Diagnostic Aids. Component Tests and General Diagnostics

Test Description

Step 1 - Step 11:

Step 12:

The numbers below refer to the step numbers on the diagnostic table.
3. This step tests for the proper operation of the circuit in the high voltage range.
4. This step 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.