Have the air conditioning system refrigerant discharged and recovered by an air conditioning technician. Disconnect the cable from the negative battery terminal. Remove the upper intake manifold for access to the A/C Expansion Valve. Locate the A/C Expansion Valve at the firewall just above the heater hoses for the front. Remove the fastener securing both line fittings to the valve and remove the lines while discarding the seals. Plug all openings quickly to minimize contamination. Remove the mounting fasteners for the valve, then remove the valve while discarding any other seals. Again, plug all openings. Installation is the reverse of removal. Install new O-rings onto the line fittings and lightly coat them with the correct refrigerant oil. Only use O-rings that are designed specifically for A/C system applications. Have the system evacuated, recharged and leak tested by the shop that discharged it. For the rear, raise the vehicle and support it securely on jackstands. Remove the rear quarter panel trim, then remove the fastener securing both line fittings to the valve and remove the lines while discarding the seals. Plug all openings quickly to minimize contamination. Remove the mounting fasteners for the valve, then remove the valve while discarding any other seals. Again, plug all openings. Installation is the reverse of removal. Install new O-rings onto the line fittings and lightly coat them with the correct refrigerant oil. Only use O-rings that are designed specifically for A/C system applications. Have the system evacuated, recharged and leak tested by the shop that discharged it.