Air Conditioning Pressure Switch
WARNING: This page does not describe the selected car, but rather 9 other vehicles, including the 2004 Ford RV Cutaway, 2004 Ford Pickup, 2004 Ford F550 Super Duty, 2004 Ford F450 Super Duty, and 2004 Ford Excursion. However, it is still accessible from the selected car via links, so may be relevant.
The A/C pressure switch (ACPSW) is used for additional A/C system pressure control. The ACPSW is also referred to as the refrigerant containment switch.
For refrigerant containment control, the normally closed high pressure contacts open at a predetermined A/C head pressure. This turns off the A/C by opening the A/C demand circuit, preventing the A/C pressure from rising to a level that would open the A/C high pressure relief valve.
An Excursion may be equipped with the optional electronic automatic temperature control (EATC).
For additional information, refer to the appropriate HVAC article.