Toyota
Dodge Durango
 Service Manual
Heating and Air Conditioning » Description and operation
Expansion valve

FRONT

DESCRIPTION

The front "H" valve-type thermal expansion valve (TXV) is located at the dash panel between the liquid and suction lines, and the evaporator coil. High-pressure, high temperature liquid refrigerant from the liquid line passes through the expansion valve orifice, converting it into a low-pressure, low-temperature mixture of liquid and gas before it enters the evaporator coil.

OPERATION

A sensor in the expansion valve control head monitors the temperature and pressure of the refrigerant leaving the evaporator coil through the suction line, and adjusts the orifice size at the liquid line to let the proper amount of refrigerant into the evaporator coil to meet the vehicle cooling requirements. Controlling the refrigerant flow through the evaporator ensures that none of the refrigerant leaving the evaporator is still in a liquid state, which could damage the compressor.

The expansion valve is a factory calibrated unit and cannot be adjusted or repaired. If faulty or damaged, the expansion valve must be replaced.

REAR

DESCRIPTION

Vehicles equipped with the optional rear overhead A/C unit have an H-type thermal expansion valve (TXV) located underneath the passenger side of the vehicle floor panel, next to the sill. It performs the same function as the front expansion valve, to monitor refrigerant temperature and pressure at the control head and meter the refrigerant entering the evaporator to meet the vehicle cooling requirements.

OPERATION

The rear expansion valve is a factory calibrated unit and cannot be adjusted or repaired. If faulty or damaged, the rear expansion valve unit must be replaced.

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    Dodge Durango Service Manual / Heating and Air Conditioning / Description and operation / Expansion valve

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