Pinpoint Test N: The Air Conditioning (A/C) is Always On - A/C Compressor Does Not Cycle

Climate Control System


Pinpoint Test N: 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, for vehicles equipped with navigation, when A/C button is pressed, a message is sent from the Front Controls Interface Module (FCIM) over the Medium Speed Controller Area Network (MS-CAN) bus to the HVAC module. The HVAC module then sends an A/C request message over the MS-CAN bus to the PCM. When MAX A/C is selected on the touch screen, the Audio Control Module (ACM) sends a message over the MS-CAN bus to the HVAC module that MAX A/C has been selected.

For vehicles not equipped with navigation, when A/C is requested, a message is sent from the HVAC module over the MS-CAN bus to the PCM.

Ignition voltage is provided to the A/C clutch relay switch through circuit SBB30 (BN/RD). When the PCM energizes the relay, ignition voltage is supplied to the A/C clutch through circuit CH401 (VT/WH). Ground is supplied for the A/C clutch through circuit GD123 (BK/GY).

This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- PCM
- A/C evaporator discharge temperature sensor
- A/C control relay
- A/C clutch air gap



PINPOINT TEST N: THE AIR CONDITIONING (A/C) IS ALWAYS ON - A/C COMPRESSOR DOES NOT CYCLE

NOTE: Before carrying out the following test, diagnose any PCM or Instrument Cluster (IC) DTCs.

NOTE: When disconnecting and reconnecting the pressure transducer electrical connector, make sure that the connector-locking device is in place and that the locking device and connector are correctly and fully seated.

N1-N4:

N5: