RAM 1500 Van V6-3.9L VIN X (1997)
Expansion Valve: Description and Operation
Fig 21 Expansion Valve Removal/Installation
Fig 12 Expansion Valves
EXPANSION VALVE
Front
The front expansion valve ("H" valve) is used to meter refrigerant into the evaporator coil in accordance with the vehicle cooling requirements.
High pressure liquid refrigerant passes through the expansion valve orifice, converting it into a low-pressure liquid before it enters the evaporator
coil.
A temperature sensor in the expansion valve control head monitors the temperature of the refrigerant leaving the evaporator coil, and adjusts the
orifice size to let the proper amount of refrigerant into the evaporator coil to meet the vehicle cooling requirements.
The front expansion valve is located at the point where the refrigerant lines join the front evaporator coil. The valve cannot be repaired or adjusted
and, if faulty or damaged, it must be replaced.
Rear
Vehicles equipped with the optional rear air conditioner have a thermally-controlled expansion valve (TXV) located inside the rear heater-A/C
unit housing, under the floor panel and behind the driver seat. It performs the same function as the front expansion valve, but uses a capillary tube
and equalizer tube arrangement to monitor refrigerant temperature at the control head.
The rear expansion valve cannot be repaired or adjusted and, if faulty or damaged, it must be replaced.