Control System Logic
All customer commands for the EMTC system come through the HVAC control head. Set the blower motor knob to any speed other than 0 to operate the system.
HVAC control module without MS-CAN
When the customer presses the A/C button on the HVAC controls, 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 HS-CAN to the PCM. The PCM controls the A/C clutch relay.
HVAC control module with MS-CAN
When the customer presses the A/C button on the HVAC controls, it sends the request to the BCM over the MS-CAN. The BCM then sends the request to the PCM over the HS-CAN. The PCM controls the A/C clutch relay.