Pinpoint Test G: The Air Conditioning (A/C) is Always On - A/C Mode Always Commanded ON
Climate Control System
Pinpoint Tests
Pinpoint Test G: The Air Conditioning (A/C) is Always On - A/C Mode Always Commanded ON
Refer to Wiring Diagram Set 54, Manual Climate Control System for schematic and connector information. Diagrams By Number
Refer to Wiring Diagrams for schematic and connector information. Diagrams By Number
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.
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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.
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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.
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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.
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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.
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