To start servicing the pressure sensor/switch, first get rid of all the refrigerant from the system and cut the negative cable of the battery before anything else. Then, unplug the wire harness connector from the HVAC pressure switch and, with an open end wrench, remove the HVAC pressure switch from its place on the liquid line. Take away the 0-ring seal from the HVAC pressure switch. Apply clean refrigerant oil to a new 0-ring seal and put it around the HVAC pressure switch for installation. Now, with an open end wrench, insert the HVAC pressure switch into the fitting on the liquid line and tighten it to 12 Nm (106 in. lbs.). Attach the wires from the wire harness connector to the switch and then attach the battery negative cable. When all is set, remove the vehicle and recharge the system with refrigerant.