Air conditioning thermostatic expansion valve (TXV) — general information
Warning: The air conditioning system is under high pressure. DO NOT loosen any hose fittings or remove any components until the system has been discharged. Air conditioning refrigerant must be properly discharged into an EPA-approved recovery/recycling unit by a dealer service department or an automotive air conditioning repair facility. Always wear eye protection when disconnecting air conditioning system fittings.
1. There are several ways that air conditioning systems convert the high-pressure liquid refrigerant from the compressor to lower-pressure vapor. The conversion takes place at the air conditioning evaporator; the evaporator is chilled as the refrigerant passes through, cooling the airflow through the evaporator for delivery to the vents. The conversion is usually accomplished by a sudden change in the tubing size. Many vehicles have a removable controlled orifice in one of the refrigerant lines at the firewall.
2. The models covered by this manual usea Thermostatic Expansion Valve (TXV) that accomplishes the same thing as a controlled orifice. To remove the TXV, have the air conditioning system discharged by a licensed air conditioning technician, then disconnect the refrigerant lines from the TXV at the firewall, and remove the heater core housing (see Heater core — replacement).
3. Remove the TXV stud (see illustration), then remove the two bolts securing the valve (see illustration). Remove the valve and replace the four 0-rings. Installation is the reverse of removal.
i.3a Remove the TXV stud from the valve
i.3b The Thermostatic Expansion Valve is located on the firewall
