Pinpoint Test G: The Air Conditioning (A/C) is Always On - A/C Mode Always Commanded ON

Climate Control System

Pinpoint Test G: The Air Conditioning (A/C) is Always On - A/C Mode Always Commanded ON

Normal Operation

Under normal operation, voltage is provided to the function selector switch. When A/C is requested, voltage is sent from the function selector switch to the A/C cycling switch. Voltage is sent from the A/C cycling switch through the A/C high pressure switch to the PCM.

Voltage is provided to the A/C clutch relay coil and switch contacts. When A/C is requested and A/C line pressures allow, a ground is provided to the A/C clutch relay coil from the PCM, energizing the A/C clutch relay. When the PCM energizes the relay, voltage is supplied to the A/C clutch from the relay. Ground is supplied for the A/C clutch.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors

- PCM

- Function selector switch

- A/C clutch relay

- A/C compressor clutch air gap

PINPOINT TEST G : THE AIR CONDITIONING (A/C) IS ALWAYS ON - A/C MODE ALWAYS COMMANDED ON

NOTE: Before carrying out the following test, diagnose any PCM DTCs.

G1 CHECK THE AIR CONDITIONING REQUEST SIGNAL (AC_REQ) PCM PID WITH THE A/C OFF

- Enter the following diagnostic mode on the scan tool: AC_REQ PCM PID.

- Place the function selector switch to the OFF position.

Does the AC_REQ PCM PID read YES?

Yes
GO to G2.

No
GO to G4.

G2 CHECK FOR VOLTAGE AT THE A/C CYCLING SWITCH

- Ignition OFF.

- Disconnect: A/C Cycling Switch C130.

- Ignition ON.

- Measure the voltage between A/C cycling switch C130-1, circuit CH434 (GY/YE), harness side and ground.





Is any voltage present?

Yes
GO to G3.

No
GO to G4.

G3 CHECK THE FUNCTION SELECTOR SWITCH TO A/C CYCLING SWITCH CIRCUIT FOR A SHORT TO VOLTAGE

- Ignition OFF.

- Disconnect: Function Selector Switch C294A.

- Ignition ON.

- Measure the voltage between A/C cycling switch C130-1, circuit CH434 (GY/YE), harness side and ground.





Is any voltage present?

Yes
REPAIR circuit CH434 (GY/YE) for a short to voltage. TEST the system for normal operation.

No
INSTALL a new function selector switch. TEST the system for normal operation.

G4 CHECK THE PCM CONNECTION

- Disconnect all the PCM connectors.

- Inspect the HVAC module connectors for:
- corrosion.
- pushed-out terminals.
- damaged terminals.


- Connect and correctly seat all the PCM connectors.

- Clear the DTCs.

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

Is the concern still present?

Yes
INSTALL a new PCM. TEST the system for normal operation.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.