Air Conditioning Clutch Switch

On factory installed A/C system, PCM receives signal voltage from Air Conditioning Clutch (ACC) switch indicating that the air conditioning compressor clutch is engaged. The PCM uses the ACC switch signal to adjust line 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 higher with air conditioning on.