On Vista, the high pressure cut off switch is located on the liquid line near the receiver/drier. The function of the switch is to disengage the compressor clutch by monitoring the discharge pressure when levels reach dangerously high levels, usually due to condenser restrictions. This switch is connected in series with the compressor clutch and is located on the liquid line near the receiver/drier.
- Start the engine and allow to idle. Turn the air conditioner ON .
- Connect an air conditioning manifold gauge to the system. The system should operate at high gauge pressure below 300 psi.
- Without allowing the engine to overheat, block the flow of air to the condenser with a cover. When the high pressure reaches the specified pressure, the clutch should disengage.
- Remove the cover. When the gauge reading falls below about 230 psi, the clutch should cycle back on.
- If faulty, replace the switch.
REMOVAL & INSTALLATION
- Disconnect the negative battery cable.
- Properly discharge the air conditioning system.
- Unplug the boot connector from the switch.
- Remove the switch from the liquid line.
- Seal the threads of the new switch with teflon tape.
- Install the switch to the line and connect the boot connector.
- Evacuate and recharge the system. Check for leaks.
- Check the switch for proper operation.