Air Conditioning Clutch Switch

On factory installed A/C system, PCM receives signal voltage from Air Conditioning Clutch (ACC) switch located on accumulator drier. This switch indicates if air conditioning compressor clutch is engaged. The PCM uses the ACC switch signal to adjust EPC pressure to compensate for additional engine load. If the ACC switch fails with closed contacts, line pressure will be slightly low with air conditioning off. If the ACC switch fails with open contacts, line pressure will be slightly high with air conditioning on.