HVAC - Manual
DTC B393B
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptors
DTC B393B 04
-
Air Conditioning Compressor Valve Control Circuit Open
DTC B393B 0B
-
Air Conditioning Compressor Valve Control Circuit High Current
Diagnostic Fault Information
Circuit/System Description
The A/C compressor is belt driven and operates when the magnetic clutch is engaged. When the A/C switch is pressed, the HVAC control module sends an A/C request message to the ECM via CAN-Bus. Therefore the ECM grounds the A/C compressor clutch relay control circuit, which will switch the A/C compressor clutch relay. With the relay contacts closed, battery voltage is supplied to the A/C compressor clutch. The A/C compressor clutch will be activated.
The performance of the A/C compressor is regulated per a lifting magnet in the A/C compressor. 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
* Ignition ON.
* The HVAC control module is ON.
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
* 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 Schematics HVAC - Manual
Connector End View Reference
Component Connector End Views Sunshade - Left (DH6)
Description and Operation
Manual HVAC Description and Operation HVAC - Manual
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Testing
1. Ignition OFF, disconnect the X1 harness connector at the G1 A/C Compressor, ignition ON.
2. Test for greater than 11 V between the control circuit terminal 2 X1 and ground.
• If less than 11 V
1. Ignition OFF, disconnect the X2 harness connector at the K33 HVAC Control Module.
2. Test for infinite resistance between the control circuit terminal 2 X1 at the G1 A/C Compressor and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the control circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K33 HVAC Control Module.
• If greater than 11 V
3. Ignition OFF, disconnect the X2 harness connector at the K33 HVAC Control Module, ignition ON.
4. Test for less than 0.3 V between the control circuit terminal 10 X2 and ground.
• If greater than 0.3 V
Repair the short to voltage on the circuit.
• If less than 0.3 V
5. Ignition OFF.
6. Test for infinite resistance between the control circuit terminal 10 X2 and ground.
• If less than infinite resistance
Repair the short to ground on the circuit.
• If infinite resistance
7. Test for less than 5 ohms between the G1 A/C Compressor control circuit terminal 1 X1 and control circuit terminal 10 X2 at the K33 HVAC Control Module harness connector.
• If 5 ohms or greater
Repair the open/high resistance in the circuit.
• If less than 5 ohms
8. Replace the G1 A/C Compressor and verify the DTC does not reset.
• If DTC resets
Replace the K33 HVAC Control Module.
• If DTC does not reset
9. All OK.
Component Testing
Static Test
1. Ignition OFF, disconnect the X1 harness connector at the G1 A/C Compressor.
2. Test for 7-15 ohms between control circuit terminal 1 X1 and control circuit terminal 2 X1.
• If not within the specified range
Replace the G1 A/C Compressor.
• If 7-15 ohms
3. Test for infinite resistance between each terminal and the G1 A/C Compressor housing/case.
• If not the specified value
Replace the G1 A/C Compressor.
• If infinite resistance
4. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Air Conditioning Compressor Replacement (LE9) Air Conditioning Compressor Replacement (LE9)Air Conditioning Compressor Replacement (V6) Air Conditioning Compressor Replacement (V6)
* Control Module References Control Module References for HVAC control module replacement, programming and setup