Buick Regal: DTC B393B
Diagnostic Instructions
- Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
- Review Strategy Based Diagnosis for an overview of the diagnostic
approach.
- Diagnostic Procedure Instructions provides an overview of each
diagnostic category.
DTC Descriptor
DTC B393B
Air Conditioning Compressor Valve Control Circuit
For symptom byte information, refer to Symptom Byte List.
Diagnostic Fault Information
Circuit/System Description
This A/C system uses a conventional clutch to engage and mechanically turn
the compressor and a
variable displacement solenoid valve to alter the amount of displacement created
by the turning of the
compressor. The HVAC control module provides both battery voltage and a pulse
width modulated
ground to the variable displacement solenoid valve. When the A/C switch is
pressed, the HVAC control
module grounds the variable displacement solenoid using a low side (PWM) signal
in order to command
the amount of compressor displacement. The performance of the A/C compressor is
based on adjusted
interior temperature and engine load.
Conditions for Running the DTC
- Ignition ON.
- The HVAC control module is ON.
Conditions for Setting the DTC
B393B 04
A PWM greater than 10% is sent 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
- The A/C compressor is disabled.
- Output will be switched off for hardware protection.
Conditions for Clearing the DTC
The condition for setting the DTC is no longer present.
Reference Information
Schematic Reference
HVAC Wiring Schematics
Connector End View Reference
Component Connector End View Index
Description and Operation
Automatic HVAC Description and Operation
Electrical Information Reference
- Circuit Testing
- Connector Repairs
- Testing for Intermittent Conditions and Poor Connections
- Wiring Repairs
Scan Tool Reference
Control Module References for scan tool information.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the Q46 A/C Compressor
Solenoid Valve.
Connect a test light between terminals 1 and 2 of the harness connector.
Ignition ON.
2. Verify the test light turns on and off when commanding the Q46 A/C Compressor
Solenoid Valve
ON and OFF with the scan tool.
- If the test light does not turn ON and OFF
- Ignition OFF, disconnect the X2 harness connector at the K33 HVAC
Control Module,
ignition ON.
- Test for less than 1 V between ground and each control circuit terminal
listed below:
- terminal 10
- terminal 11
- If 1 V or greater, repair the short to voltage on the circuit.
- Go to next step: If less than 1 V
- Ignition OFF.
- Test for infinite resistance between ground and each control circuit
terminal listed below:
- terminal 10
- terminal 11
- If less than infinite resistance, repair the short to ground on the
circuit.
- Go to next step: If infinite resistance
- Test for less than 2 Ω in each of the control circuits end to end listed
below:
- Q46 A/C Compressor Solenoid Valve terminal 1 and K33 HVAC Control
Module
terminal 10
- Q46 A/C Compressor Solenoid Valve terminal 2 and K33 HVAC Control
Module
terminal 11
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- Go to next step: If less than 2 Ω, replace the K33 HVAC Control
Module.
- Go to next step: If the test light turns ON and OFF
3. Test the Q46 A/C Compressor Solenoid Valve or replace the G1 A/C
Compressor.
Component Testing
A/C Compressor Solenoid Valve Test
1. Ignition OFF, disconnect the harness connector at the Q46 A/C Compressor
Solenoid Valve.
2. Test for 7 - 15 Ω between B+ terminal 2 and control terminal 1.
- If less than 7 Ω or greater than 15 Ω
Replace the G1 A/C Compressor.
- Go to next step: If between 7 - 15 Ω
3. Test for infinite resistance between each terminal and the Q46 A/C
Compressor Solenoid Valve
housing/case.
- If less than infinite resistance
Replace the G1 A/C Compressor.
- Go to next step: If infinite resistance
4. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
- HVAC Component Replacement Reference
- Control Module References for control module replacement, programming
and setup
READ NEXT:
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic
approach.
Diag
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic
approach.
Diag
NOTE: The following steps must be completed before using the symptom
tables:
1. Perform the Diagnostic System Check - Vehicle before using the HVAC System
Malfunction
procedure in order to verify th
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DRIVE BELT REPLACEMENT
Fig. 1: Drive Belt Routing Diagram (2.0L)
Preliminary Procedure
Front Wheelhouse Liner Replacement (LTG).
Drive Belt
Procedure
Using a suitable tool, slowly
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic
approach.
Diagnostic Procedure Instructions provides an overview of each
diagnostic category.
DTC Descriptors
D