A/C Request Signal

This signal is transmitted two different ways depending on the content option, the first is communicated Class II from the HVAC Controller to the PCM that an A/C mode is selected (CJ2). The second is a 12 volt signal from the HVAC Controller to the PCM, the 12.0 volt signal indicates that an A/C mode is selected (CJ3, C60). 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 (CJ3, C60) or PCM Controlled A/C Circuit Diagnosis (CJ2) 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 HVAC should be used.