Diagnostic Instructions

DTC Descriptors

DTC B393B 04: Air Conditioning Compressor Valve Control Circuit Open circuit

DTC B393B 0B: Air Conditioning Compressor Valve Control Circuit Current Above Threshold

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
A/C Compressor B+	B393B 04	B393B 04	--	--
A/C Compressor Control	B393B 04	B393B 04	B393B 0B	1
A/C Compressor Malfunction

Circuit/System Description

The HVAC control module supplies battery 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

P393B 04

Measured current is above threshold of 815 mA.

P393B 0B

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

Action Taken When the DTC Sets

P393B 04

The A/C compressor is disabled.

P393B 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

Automatic 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 11 V between the B+ circuit terminal B and ground.

⇒	If less than the specified range, test the B+ 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 7-10 Ω between control circuit terminal A and B+ 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.