F 350 4WD Pickup V8-351 5.8L VIN H EFI (1997)
Refrigerant Pressure Sensor / Switch: Description and Operation
A/C Pressure Cutoff Switch
Single Function
An A/C pressure cut-off switch is used to interrupt A/C compressor operation in the event of high system discharge pressures that could result in
the loss of refrigerant charge. The switch is located in the discharge line between the compressor and the A/C condenser core. The switch is
sensitive to the discharge pressure and functions to interrupt the A/C compressor operation if the discharge pressure exceeds a setting of
2965-3241 kPa (430-470 psi). The single function switch only controls the circuit to the A/C cycling switch. When replacing the switch, tighten to
7-13 Nm (62-115 Lb-in).
The A/C pressure cut-off switch has a set of electrical contacts which are normally closed. When compressor head pressure rises to approximately
2965-3241 kPa (430-470 psi), the contacts open and the compressor operation is shut OFF.
When compressor head pressure drops to approximately 1586-2000 kPa (230-290 psi), the contacts close again and allow operation of the A/C
compressor. Shutting down compressor operation prior to the pressure relief valve set point ensures containment of the refrigerant within the A/C
system.
