For 1990-2009 cars

### 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 B013B 00: Coil Compressor Stroke Control Circuit

### Circuit/System Description

The A/C system uses a clutchless variable stroke compressor with an electrical control valve which is used to alter the displacement of the compressor, this process is known as electronic control valve displacement (ECVD). ECVD at the compressor is controlled by pulse width modulated (PWM) signal supplied by the HVAC control module via the A/C compressor supply voltage circuit. When the A/C button is pressed, the HVAC control module grounds the A/C compressor low reference circuit completing the circuit and in turn allowing the compressor to operate. The signal returned to the HVAC control module via the A/C low reference circuit is also used in comparison to the supplied signal to confirm correct compressor operation and ECVD positioning.

### Conditions for Running the DTC

• | System voltage is between 9 - 16 Volts.

• | Ignition switch is in the ON position.

### Conditions for Setting the DTC

The DTC will set when the A/C compressor is operating and the evaporator temperature fails to drops 5 degrees or more within a 30 second time period.

### Action Taken When the DTC Sets

The A/C compressor circuits are deactivated.

### Conditions for Clearing the DTC

• | The DTC becomes history after the condition for setting the DTC is no longer present.

• | The history DTC clears after 50 fault-free ignition cycles.

• | The DTC can be cleared using a scan tool.

### Reference Information

#### Schematic Reference

HVAC Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References

### Circuit/System Verification

Ignition ON, A/C ON, blower speed HIGH, temperature set to COLD, mode set to PANEL. Using a scan tool, observe that the evaporator temperature drops by more than 5° C over a 1 minute period. Useing the scan tool command the ECVD compressor ON it will engage at maximum displacement - this should register on the scan tool display as a PWM of approximately 82%, after 6 seconds the ECVD compressor will automatically disengage and PWM will return to 0%.

### Circuit/System Testing

1. Disconnect the HVAC control module X1 electrical connector.
2. Test the A/C compressor clutch low reference circuit terminal 6 for a short to ground, voltage or an open/high resistance.
3. Test the A/C compressor clutch supply voltage circuit terminal 7 for a short to ground, voltage or an open/high resistance.

⇒ | If all circuits test normal, replace the HVAC control module.

### Component Testing

Ignition OFF, disconnect the ECVD compressor harness connector and measure the component resistance. Verify that 8.5Ω - 15.7Ω is displayed. If outside of the specified range, replace the ECVD compressor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Air Conditioning Compressor Replacement

• | Control Module References for HVAC control module replacement, setup, and programming.