Possible Causes

ATTEMPT TO COMMUNICATE WITH THE PCM, THE BCM, AND THE IPM

CHECK FOR HVAC RELATED DTCS IN THE POWERTRAIN CONTROL MODULE (PCM)

CHECK FOR BODY CONTROL MODULE (BCM) DTCS

CHECK FOR INTEGRATED POWER MODULE (IPM) DTCS

CHECK FOR ACTIVE HVAC DTCS AND SYSTEM TESTS FAULT MESSAGES

CHECK FOR HVAC RELATED DTCS IN THE PCM

Perform MANUAL A/C SYSTEM TEST