Test E: The Air Conditioning (A/C) Is Always On
PINPOINT TEST E: THE AIR CONDITIONING (A/C) IS ALWAYS ONNormal Operation
Under normal operation, when A/C is requested, a ground signal is sent from the HVAC module to the smart junction box (SJB) through circuit 1397 (GY/RD). The SJB then transmits an A/C request message through the high-speed controller area network (HS-CAN) bus to the PCM.
4.0L only
Voltage is provided to the A/C cycling switch through circuit 391 (RD/YE). If the A/C cycling switch is closed (sufficient pressure) voltage is sent from the A/C cycling switch to the PCM (4.0L) through circuit 198 (DG/OG)/420 (DB/YE). When the PCM receives voltage from the pressure switch and the A/C pressure transducer does not indicate excessive pressure, the PCM provides a ground for the A/C clutch relay through circuit 321 (GY/WH).
4.6L and 5.4L only
Voltage is provided to the A/C cycling switch through circuit 391 (RD/YE). If the A/C cycling switch is closed (sufficient pressure) voltage is sent from the A/C cycling switch to the dual-function pressure switch (4.6L and 5.4L) through circuit 198 (DG/OG). If the dual-function pressure switch (4.6L and 5.4L) is closed (pressure not excessive), voltage is sent to the PCM through circuit 420 (DB/YE). When the PCM receives voltage from the pressure switches, the PCM provides a ground for the A/C clutch relay through circuit 321 (GY/WH).
When the relay is activated, ignition voltage is supplied to the A/C clutch solenoid through circuit 883 (PK/LB). Ground is supplied for the A/C clutch through circuit 1205 (BK).
- DTC B2175 A/C Request Signal Circuit Short to Ground - The module senses a continuous short to ground on the A/C request circuit.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- PCM
- SJB
- HVAC module
- A/C cycling switch
- A/C control relay
- A/C clutch air gap
E1:
E2-E5:
