Ford Mustang (1999-2004) Service Manual: Dual-Function Pressure Switch (4.6L)

The dual-function pressure switch is used to interrupt A/C compressor operation in the event of high system discharge pressures.

• The dual-function pressure switch is mounted on a Schrader valve-type fitting on the high pressure side of the A/C manifold and tube.
• It is not necessary to discharge the refrigerant system to remove the dual-function pressure switch.
• A valve depressor, located inside the threaded end of the dual-function pressure switch, presses on the Schrader valve stem.
• This allows the dual-function pressure switch to monitor the compressor discharge pressure.
• When the compressor discharge pressure rises, the switch contacts open, disengaging the A/C compressor. When the pressure drops, the contacts close to allow operation of the A/C compressor. For specifications regarding operating pressure(s), refer to Section.

The dual-function pressure switch has a second set of electrical contacts used for high-speed cooling fan control.

When the compressor discharge pressure rises, the contacts close and engage the high speed fan control. When the pressure drops, the contacts open and the high speed fan control is disengaged.

Refrigerant Containment Switch (3.8L)

The refrigerant containment switch is used to interrupt A/C compressor operation in the event of high system discharge pressures.

• The refrigerant containment switch is mounted on a Schrader-type valve fitting on the high pressure side of the compressor manifold and tube assembly.
• A valve depressor, located inside the threaded end of the refrigerant containment switch, presses on the Schrader valve stem.
• This allows the refrigerant containment switch to monitor the A/C compressor discharge pressure.
• When the A/C compressor discharge pressure rises, the switch contacts open, disengaging the A/C compressor. When the pressure drops, the contacts close to allow operation of the A/C compressor. For additional information regarding operating pressure(s), refer to Section.
• It is not necessary to discharge the refrigerant system to remove the refrigerant containment switch.