Air Conditioning Clutch Switch
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2002 Lincoln Navigator, 2002 Ford Expedition, 2001 Lincoln Navigator, 2001 Ford RV Cutaway, and 2001 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.
On factory installed A/C system, PCM receives signal voltage from Air Conditioning Clutch (ACC) switch, located on accumulator, indicating that air conditioning compressor clutch is engaged. PCM uses ACC switch signal to adjust line pressure to compensate for additional engine load. If ACC switch fails with closed contacts, line pressure will be slightly lower with air conditioning off. If ACC switch fails with open contacts, line pressure will be slightly higher with air conditioning on.