OPERATION

The contacts in the A/C high pressure switch open and close causing the engine control module (ECM) to turn the A/C compressor clutch on and off. This prevents A/C compressor operation when the discharge pressure approaches high levels, and also reduces electrical surging from A/C clutch engagement.

The A/C high pressure switch controls the electric cooling fan operation by monitoring refrigerant line pressures. When the A/C discharge line pressure rises above 1900 to 2200 kPa (280 to 320 psi) the fan will turn on. The cooling fan will turn off when the A/C discharge line pressure drops to 1600 kPa (235 psi).

The A/C high pressure switch contacts open when the A/C discharge line pressure rises above 3100 to 3375 kPa (450 to 490 psi). The A/C high pressure switch contacts close when the A/C discharge line pressure drops to 1860 to 2275 kPa (270 to 330 psi).

The A/C high pressure switch is factory-calibrated and cannot be adjusted or repaired and must be replaced if found inoperative or damaged.