HVAC - Manual

DTC P0537 or P0538

Circuit Description

The HVAC control module monitors the evaporator temperature via the evaporator temperature sensor. When the air is cold, the sensor resistance and signal voltage are high. When the air is warm, the sensor resistance and signal voltage are low.

DTC Descriptors

This diagnostic procedure supports the following DTC:

DTC P0537
- Evaporator Air Temperature Sensor Circuit Low Voltage

DTC P0538
- Evaporator Air Temperature Sensor Circuit High Voltage

Conditions for Running the DTC

The ignition is turned ON.

Conditions for Setting the DTC

The HVAC control module detects the evaporator temperature sensor signal circuit is less than 0.443 volts or greater than 4.55 volts.

Action Taken When the DTC Sets

The air conditioning (A/C) compressor will be disabled.

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.

Test Description

Step 1 - Step 8:

Step 9 - Step 13:

The numbers below refer to the step numbers on the diagnostic table.
4. This step tests for the proper operation of the circuit in the high voltage range.
5. This step tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens upon performing this test, the signal circuit has a short to voltage.