A/C Request (Hybrid)

When A/C is requested, the ACCM engages the A/C electric compressor when all of the following conditions are met:

The PCM does not detect excessively high or low refrigerant pressure from the A/C pressure transducer.
The PCM does not detect an ambient air temperature below approximately 2deg.C (35.6deg.F).
The PCM does not detect temperatures from the MAF sensor, IAT sensor (as equipped) that does not correlate with other temperature sensor readings at ignition ON. Most Mass Airflow (MAF) sensors have an integrated Intake Air Temperature (IAT) sensor).
The PCM does not receive a message from the HVAC control module detecting an evaporator temperature below approximately 1deg.C (33.8deg.F).

Compressor control and the evaporator temperature are a function of many parameters, not a straight on off to avoid freezing the evaporator. The PCM monitors multiple temperature sensors correlation including, but not limited to, AAT, CACT, CHT, ECT, IAT, IAT2, MAF, MAPT, TCB and TCIPT Parameter Identifications (PIDs) (as applicable).

This soak period allows the Ambient Air Temperature (AAT) sensor and the other temperature sensors to stabilize and not differ by greater than a calibrated value, typically 18 deg.C (32.4 deg.F). If a sensor input is found to be reporting a temperature imbalance the PCM sends a message out to the SOBDMC which does not allow the A/C electric compressor to engage.

The A/C electric compressor, instead of cycling on and off like a traditional A/C compressor, the SOBDMC raises or lowers the A/C electric compressor speed based on multiple inputs from the PCM and the HVAC control module.