With the temperature switch at the HVAC control, the desired air temperature flap position can be put in. The selected value is sent to the HVAC control module via the LIN-Bus. The HVAC control module supplies a 12 V reference voltage to the stepper motor and energizes the 4 stepper motor coils with a pulsed ground signal. The stepper motor moves the temperature flap into the calculated position, in order to reach the selected temperature.

Check the following mechanical fault sources:

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Manual HVAC Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

1. Measure actual evaporator temperature using a thermometer. Compare this value to the scan tool A/C Evaporator Temperature Sensor parameter. The measured temperature should be within 5°C (9°F) difference of parameter value.

⇒	If not within the specified range, refer to DTC B3933

2. Engine is running, activate and deactivate the A/C switch. Verify the A/C compressor can be activated and deactivated.

⇒	If the A/C compressor cannot be activated or deactivated, refer to Air Conditioning Compressor Malfunction

3. Verify the engine reaches its operating temperature.

1. Ignition ON, turn the temperature knob in all positions. Verify the scan tool Left Temperature Knob Position parameter. The reading should be between -7 to +7 and change with the knob position. At the left end position the reading should be 16 and at the right end position -16.

⇒	If not the specified value, replace the A26 HVAC Control

2. If all circuits test normal, replace the M6L Air Temperature Actuator - Left and verify the M6L Air Temperature Actuator - Left can be put into all positions. If the M6L Air Temperature Actuator - Left cannot be put into all positions, replace the K33 HVAC Control Module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.