A/C Signal: Description and Operation

A/C Request Signal

This signal is transmitted through a 12 volt signal from the Front (C60) HVAC Controller to the PCM, the 12.0 volt signal indicates that an A/C mode is selected. The PCM uses this information to adjust the idle speed before turning on the A/C clutch. If this signal is not available to the PCM, the A/C Compressor will be inoperative. Refer to PCM Controlled A/C Circuit Diagnosis for A/C clutch wiring diagrams and diagnosis of A/C clutch electrical system. When diagnosing the refrigerant portion of the HVAC system, the Cooling Insufficient, A/C System diagnosis in Heating and Air Conditioning should be used.