Low pressure cut-off switch. Rear overhead air conditioner

Low pressure cut-off switch


The low pressure cut-off switch is located on the suction line jumper tube. The switch is screwed onto a fitting that contains a Schrader-type valve, which allows the switch to be serviced without discharging the refrigerant system. The fitting is equipped with an O-ring to seal the switch connection.


The low pressure cut-off switch is connected in series electrically with the high pressure cut-off switch, the heater-A/C controls, the Electronic Cycling Clutch Switch (ECCS), between ground, and the Powertrain Control Module (PCM). The switch contacts open and close causing the PCM to turn the compressor clutch on and off. This regulates the refrigerant system pressure, ensuring a sufficient amount of refrigerant throughout the system.

The low pressure cut-off switch contacts will open when the suction pressure is about 48 to 90 kPa (7 to 13 psi) or lower. The switch contacts will close when the suction pressure rises to about 103 to 193 kPa (15 to 28 psi) or above. Lower ambient temperatures, below about -1 C (30 F), will also cause the switch contacts to open. This is due to the pressure/temperature relationship of the refrigerant in the system.

The low pressure cut-off switch is a factory-calibrated unit. It cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.

Rear overhead air conditioner


A rear overhead air conditioning unit is an available option to supplement the output of the front air conditioner, for increased rear seat passenger comfort.

This unit includes a roof-mounted evaporator coil and a blower motor with a wide squirrel-cage type blower wheel. A four position (three speeds plus off) rear blower motor switch is mounted in the headliner behind the right front seat position, where it is accessible to both the driver and the second seat passengers.


The wide and shallow rear unit is positioned between the front and second seats to provide ample headroom for all vehicle occupants. The headliner is molded to cover the unit and includes an integral air intake grille toward the front of the unit, and an opening for a snap-in outlet bezel that includes four adjustable outlet barrels toward the rear of the unit.

A condensate tray is integral to the lower unit housing, and water is drained out of the unit through hoses located behind the trim on each of the B-pillars.

The rear overhead air conditioner will provide cooling only when an air conditioning mode is selected with the front heater and A/C controls, but the rear blower will operate independent of the front controls to circulate the interior air if desired.

    Dodge Durango (DN) 1998-2003 Service Manual


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