Dual-Function Pressure Switch (4.6L and 5.4L)

WARNING: This page is about a different car, the 2009 Ford Mustang. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: It is not necessary to recover the refrigerant before removing the dual-function pressure switch.

The dual-function pressure switch includes 2 separate sets of contacts that are opened at 2 different pressures.

The first set of contacts in the dual-function pressure switch is used to interrupt A/C compressor operation in the event of excessively high discharge pressure in the high-pressure side of the refrigerant system. The PCM monitors the first set of contacts in the dual-function pressure switch in series with the A/C cycling switch. When the ACCS circuit is open, the PCM will disengage the A/C compressor clutch.

The second set of contacts in the dual-function pressure switch is used by the PCM to engage the high speed cooling fan. When the A/C pressure rises above a preset level, the second set of contacts will close and the high-speed cooling fan will be engaged.

For specifications regarding operating pressure(s), refer to CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS .