Pinpoint Test L: The Air Conditioning (A/C) Is Always On - A/C Compressor Does Not Cycle
Climate Control System
Pinpoint Tests
Pinpoint Test L: The Air Conditioning (A/C) is Always On - A/C Compressor Does Not Cycle
Refer to Wiring Diagram Set 54, Manual Climate Control System for schematic and connector information. Diagrams By Number
Refer to Wiring Diagram Set 55, Automatic Climate Control System for schematic and connector information. Diagrams By Number
Normal Operation
Under normal operation, when A/C is requested, the climate control assembly or HVAC module sends voltage to the A/C cycling switch. The PCM receives input from the A/C cycling switch, when closed (sufficient pressure). The A/C cycling switch is used for A/C compressor cycling. The switch is used by the PCM to turn off the A/C compressor before the line pressures are low enough to drop the evaporator temperature excessively low and freeze the condensation.
Voltage is provided to the A/C clutch relay switch. 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
- A/C clutch relay
- Function selector switch
- HVAC module
- A/C clutch air gap
PINPOINT TEST L: THE AIR CONDITIONING (A/C) IS ALWAYS ON - A/C COMPRESSOR DOES NOT CYCLE
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L1 CHECK THE AIR CONDITIONING CYCLING SWITCH (ACCS) PCM PID WITH THE A/C OFF
- Enter the following diagnostic mode on the scan tool: ACCS PCM PID.
- Place the function selector switch in the OFF position or press the OFF manual override button on the HVAC module.
- Does the ACCS PCM PID read OFF?
Yes
GO to L2.
No
GO to L4.
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L2 CHECK FOR VOLTAGE TO THE A/C COMPRESSOR CLUTCH FIELD COIL
- Ignition OFF.
- Disconnect: A/C Compressor Clutch Field Coil C100.
- Ignition ON.
- Measure the voltage between A/C compressor clutch field coil C100-1, circuit 321 (GY/WH), harness side and ground.
- Is any voltage present?
Yes
GO to L3.
No
ADJUST the A/C compressor clutch gap. REFER to Air Conditioning (A/C) Clutch Air Gap Adjustment Adjustments. TEST the system for normal operation.
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L3 CHECK CIRCUIT 321 (GY/WH) FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: A/C Clutch Relay.
- Ignition ON.
- Measure the voltage between A/C compressor clutch field coil C100-1, circuit 321 (GY/WH), harness side and ground.
- Is any voltage present?
Yes
REPAIR circuit 321 (GY/WH) for a short to voltage. TEST the system for normal operation.
No
INSTALL a new A/C clutch relay. CHECK the A/C clutch diode. INSTALL a new diode, if necessary. TEST the system for normal operation.
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L4 CHECK CIRCUIT 348 (VT) FOR VOLTAGE
- Ignition OFF.
- Disconnect: A/C Cycling Switch C1081.
- Ignition ON.
- Measure the voltage between A/C cycling switch C1081-4, circuit 348 (VT), harness side and ground.
- Is any voltage present?
Yes
GO to L5.
No
GO to L6.
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L5 CHECK CIRCUIT 348 (VT) FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: HVAC Module C228B.
- Ignition ON.
- Measure the voltage between A/C cycling switch C1081-4, circuit 348 (VT), harness side and ground.
- Is any voltage present?
Yes
REPAIR circuit 348 (VT) for a short to voltage. TEST the system for normal operation.
No
INSTALL a new function selector switch or HVAC module. REFER to Climate Control Function Selector Switch. TEST the system for normal operation.
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L6 CHECK CIRCUIT 883 (PK/LB) FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: PCM C175B.
- Ignition ON.
- Measure the voltage between A/C cycling switch C1081-1, circuit 883 (PK/LB), harness side and ground.
- Is any voltage present?
Yes
REPAIR circuit 883 (PK/LB) for a short to voltage. TEST the system for normal operation.
No
INSTALL a new PCM. TEST the system for normal operation.
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