Dual Function Pressure Switch

DUAL FUNCTION PRESSURE SWITCH

The dual function pressure switch (DFPS) 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 compressor manifold and tube assembly.
- A valve depressor, located inside the threaded end of the DFPS, presses on the Schrader valve stem.
- This allows the DFPS to monitor the compressor discharge pressure.
- The DFPS has 2 sets of electrical contacts. One set of contacts is normally closed and is used for A/C high-pressure cutoff.
- When the A/C compressor discharge pressure rises, the switch contacts open, disengaging the A/C compressor. When the compressor discharge pressure drops, the switch contacts return to the CLOSED position and A/C compressor operation resumes. For specifications regarding operating pressures, Refer to Heating and Air Conditioning.
- The second set of electrical contacts in the DFPS is used for engine cooling fan control.
- It is not necessary to recover the refrigerant to remove the DFPS.