Vauxhall Workshop Service and Repair Manuals

DTC B393B

Diagnostic Instructions

DTC Descriptors

Diagnostic Fault Information

Circuit/System Description

The HVAC control module supplies voltage to the A/C compressor. When the A/C switch is pressed, the HVAC control module provides a pulse width modulation (PWM) signal to the A/C compressor in order to command the performance of the A/C compressor. The performance of the A/C compressor is regulated according to adjusted interior temperature on the basis of characteristic lines. Therefore the HVAC control module grounds the A/C compressor with the PWM signal.

Conditions for Running the DTC

Conditions for Setting the DTC

B393B 04

A PWM greater than 10% is send out but no current is read back.

B393B 0B

Measured current is above threshold of 815 mA.

Action Taken When the DTC Sets

B393B 04

The A/C compressor is disabled.

B393B 0B

Conditions for Clearing the DTC

The condition for setting the DTC is no longer present.

Reference Information

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

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the Q46 Air Conditioning Compressor Valve.
2. Ignition ON, test for greater than 9 V between the control circuit terminal B and ground.

⇒	If less than the specified range, test the control circuit for a short to ground or an open/high resistance.

3. Ignition OFF, disconnect the X2 harness connector at the K33 HVAC Control Module.
4. Ignition ON, test for less than 0.3 V between the control circuit terminal 10 X2 and ground.

⇒	If greater than the specified range, test the control circuit for a short to voltage.

5. Ignition OFF, test for infinite resistance between the control circuit terminal 10 X2 and ground.

⇒	If less than the specified range, test the control circuit for a short to ground.

6. Test for less than 5 Ω between the Q46 Air Conditioning Compressor Valve control circuit terminal A and control circuit terminal 10 X2 at the K33 HVAC Control Module harness connector

⇒	If greater than the specified value, test the control circuit for an open/high resistance.

7. If all circuits test normal, test or replace the Q46 Air Conditioning Compressor Valve and verify the DTC does not reset.

⇒	If the DTC resets, replace the K33 HVAC Control Module.

Component Testing

Static Test

1. Ignition OFF, disconnect the harness connector at the Q46 Air Conditioning Compressor Valve.
2. Test for 7-15 Ω between B+ circuit terminal A and control circuit terminal B.

⇒	If not within the specified range, replace the Q46 Air Conditioning Compressor Valve.

3. Test for infinite resistance between each terminal and the Q46 Air Conditioning Compressor Valve housing/case.

⇒	If not the specified value, replace the Q46 Air Conditioning Compressor Valve.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.