A/C Request

The HVAC control module uses a dedicated wire to send the A/C request message to the BCM. The BCM sends the A/C request through the High Speed Controller Area Network (HS-CAN) to the PCM.

When an A/C request is received by the PCM, the PCM engages the A/C clutch relay when:

• the refrigerant pressure isn't excessively high or low.
• the engine coolant temperature isn't excessively high.
• the ambient air temperature is above 6 C (43 F).
• a WOT condition is not present.
• the evaporator discharge air temperature is above 7 C (45 F).