The rear air conditioning system uses a thermal expansion valve (TXV). The thermal expansion valve consists of the following components:

At the high pressure liquid inlet, a fine mesh screen prevents dirt, filings, or other foreign material from entering the valve orifice. High pressure liquid refrigerant enters the valve through this screen from the condenser. The liquid then passes on to the valve seat and the orifice, where the liquid is changed into a low pressure liquid. The liquid then leaves the valve and flows into the evaporator core. In the evaporator core, the liquid absorbs heat causing the liquid to change into a low pressure vapor, which then leaves the evaporator core. The capillary tube is clamped to the low pressure vapor line just below the outlet of the evaporator. The capillary tube is held in contact with the rear evaporator outlet tube by a metal clip placed near the end of the tube.

The TXV is located on the rear evaporator inlet. The TXV provides a restriction to the high pressure liquid refrigerant in the liquid line, metering the flow of refrigerant to the evaporator as low pressure liquid. The TXV assembly contains a capillary tube, which monitors the temperature rises and decreases the refrigerant flow when the evaporator outlet temperature lowers. Service the TXV only as a replacement assembly.