A/C Pressure Switch (ACPSW)
WARNING: This page is about a different car, the 1995 Ford Windstar. However, it is still accessible from the selected car via links, so may be relevant.
The ACPSW is used for additional A/C system pressure control. The ACPSW is also referred to as the refrigerant containment/fan function switch. The normally open medium pressure contacts close at a predetermined A/C head pressure. This grounds the ACPSW circuit input to the PCM. The PCM will then turn on high speed fan to help reduce pressure.