The HVAC Pressure Switch is mounted in the refrigerant line between the condenser and the evaporator, detecting low (28 psi) and high (455 psi) refrigerant line pressure, shutting the system off if the pressure falls below or exceeds these values. Begin by having the refrigerant discharged and recovered by an air conditioning technician. Next, set the parking brake, block the rear wheels, and raise the front of the vehicle, supporting it securely on jackstands, then remove the under-vehicle splash shield. Locate the switch on the right side of the vehicle and unplug the electrical connector from the HVAC Pressure Switch, ensuring clarity by removing the front bumper cover if necessary. Unscrew the pressure switch from the line, holding the stationary fitting with an open-end wrench to prevent damage. Lubricate the switch O-ring with clean refrigerant oil of the correct type, then screw the new switch onto the refrigerant line and tighten it securely. Reconnect the electrical connector and have the system evacuated, charged, and leak tested by an air conditioning technician.