Test K: The Air Conditioning (A/C) Is Always On

PINPOINT TEST K: THE AIR CONDITIONING (A/C) IS ALWAYS ON

K1-K3:

K4-K8:

K8-K11:

Normal Operation
Under normal operation, when A/C is requested, in the electronic automatic temperature control (EATC) module system, a message is sent over the medium speed controller area network (MS-CAN) bus to the instrument cluster, then from the instrument cluster through the high speed controller area network (HS-CAN) bus to the powertrain control module (PCM); or in electronic manual temperature control (EMTC) systems, voltage is sent to the instrument cluster through circuit CH434 (GY/YE), then a message is sent from the instrument cluster through the HSCAN bus to the PCM.

Ignition voltage is provided to the A/C clutch relay switch. 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 GD120 (BK/GN).

Possible Causes
- An short to ground on circuit CH434 (GY/YE)
- An short to voltage on circuit CH401 (VT/WH)
- PCM
- EATC module
- EMTC module
- A/C evaporator discharge temperature sensor
- A/C pressure transducer
- A/C control relay
- A/C compressor