Diagnostic Routine M

Diagnostic Routine M

Diagnostic Overview

The Air Conditioning (AC) Is Inoperative

Refer to Wiring Diagram Set 55 for schematic and connector information Electrical Diagrams.

Normal Operation and Fault Conditions

REFER to Control System Logic.

REFER to Controls and Compressor Cycling.

REFER to Air Conditioning (AC) Pressure Transducer.

REFER to Evaporator Temperature Sensor.

Visual Inspection and Diagnostic Pre-checks

- Inspect BJB (Battery Junction Box) fuse 27 (15A).

- Inspect the A/C (Air Conditioning) clutch relay.

Pinpoint Test

1. CHECK THE A/C (Air Conditioning) PRESSURE SENSOR (ACP_PRESS) PID (Parameter Identification)

1. Using a scan tool, view PCM (Powertrain Control Module) PIDs (Parameter Identifications).

2. With a manifold gauge set connected, compare the pressure readings of the manifold gauge set and the PCM (Powertrain Control Module) PID (Parameter Identification) ACP_PRESS.

Are the pressure values of the manifold gauge set and the PID (Parameter Identification) similar?






2. CHECK THE AIR CONDITIONING REQUEST SIGNAL (AC_REQ) PID (Parameter Identification) WITH THE A/C (Air Conditioning) ON

1. KOER (Key ON Engine Running).

2. Using a scan tool, view PCM (Powertrain Control Module) PIDs (Parameter Identifications).

3. Monitor the AC_REQ, PCM (Powertrain Control Module) PID (Parameter Identification).

4. Select MAX A/C on the HVAC (Heating, Ventilation, and Air Conditioning) module.

Does the PID (Parameter Identification) read YES?






3. CHECK THE AIR CONDITIONING COMPRESSOR COMMANDED STATE (ACC_CMD) PCM (Powertrain Control Module) PID (Parameter Identification) WITH THE A/C (Air Conditioning) ON

1. Using a scan tool, view PCM (Powertrain Control Module) PIDs (Parameter Identifications).

2. Monitor the ACC_CMD, PCM (Powertrain Control Module) PID (Parameter Identification).

Does the PID (Parameter Identification) read ON?






4. CHECK THE A/C (Air Conditioning) CLUTCH RELAY FOR VOLTAGE SUPPLY CIRCUIT FOR AN OPEN

1. Ignition ON.

2. Measure:





Is the voltage greater than 11 volts?






5. CHECK THE A/C (Air Conditioning) COMPRESSOR CLUTCH FIELD COIL VOLTAGE SUPPLY CIRCUIT FOR AN OPEN

1. Disconnect: A/C (Air Conditioning) Clutch Relay.

2. KOER (Key ON Engine Running).

3. Connect a fused jumper wire:





Does the A/C (Air Conditioning) compressor clutch engage?






6. CHECK THE A/C (Air Conditioning) COMPRESSOR CLUTCH FIELD COIL VOLTAGE SUPPLY CIRCUIT FOR AN OPEN

1. Ignition OFF.

2. Disconnect: A/C (Air Conditioning) Compressor Clutch Field Coil.

3. Measure:





Is the voltage greater than 11 volts?






7. CHECK THE A/C (Air Conditioning) COMPRESSOR CLUTCH FIELD COIL GROUND CIRCUIT FOR AN OPEN

1. Measure:





Is the voltage greater than 11 volts?






8. CHECK THE A/C (Air Conditioning) COMPRESSOR CLUTCH AIR GAP

1. Measure the A/C (Air Conditioning) compressor clutch air gap at 3 equally spaced locations between the clutch hub and the A/C (Air Conditioning) compressor clutch pulley.





Is the A/C (Air Conditioning) compressor clutch air gap greater than 0.6 mm (0.0236 in)?






9. CHECK FOR CORRECT HVAC (Heating, Ventilation, and Air Conditioning) MODULE OPERATION

1. Ignition OFF.

2. Disconnect and inspect the HVAC (Heating, Ventilation, and Air Conditioning) module connectors.

3. Repair:

- corrosion (replace connector or terminals- clean module pins)
- damaged or bent pins- replace terminals/pins
- pushed-out pins- replace pins as necessary

4. Reconnect the HVAC (Heating, Ventilation, and Air Conditioning) module connectors. Make sure they seat and latch correctly.

5. Operate the system and verify the concern is still present.

Is the concern still present?






10. CHECK FOR CORRECT PCM (Powertrain Control Module) OPERATION

1. Ignition OFF.

2. Disconnect and inspect the PCM (Powertrain Control Module) connectors.

3. Repair:

- corrosion (replace connector or terminals- clean module pins)
- damaged or bent pins- replace terminals/pins
- pushed-out pins- replace pins as necessary

4. Reconnect the PCM (Powertrain Control Module) connectors. Make sure they seat and latch correctly.

5. Operate the system and verify the concern is still present.

Is the concern still present?