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Services > Air Conditioning & Heating> Air Conditioning System Parts > AC Expansion Valve
Function: The restriction point at which the refrigerant expands and cools. (Vehicles are equipped with either an expansion valve of an orifice tube)
Signs of Wear: Lack of cooling within the vehicle cabin.
The expansion valve represents the point of separation between the high pressure and low pressure sections in the refrigerant circuit. It is installed upstream of the evaporator. To achieve optimum cooling capacity in the evaporator, the refrigerant flow is controlled by the expansion valve depending on the temperature. As a result, complete evaporation of the liquid refrigerant is ensured and gaseous refrigerant arrives at the compressor only. Expansion valves may differ in their design.
How they work
The liquid refrigerant - arriving through the filter dryer from the condenser - flows through the expansion valve and is injected into the evaporator. The evaporating refrigerant releases evaporation cold. This causes temperature to drop. To achieve optimum cooling capacity in the evaporator, the refrigerant flow is controlled by the expansion valve depending on the temperature. At the end of the evaporator, the refrigerant is transported through the expansion valve to the compressor. If the refrigerant temperature increases at the end of the evaporator, it expands in the expansion valve. This results in an increase of the refrigerant flow (injection quantity) to the evaporator. If the refrigerant temperature lowers at the end of the evaporator, the volume in the expansion valve decreases. As a result, the expansion valve reduces the refrigerant flow to the evaporator.
Effects of failure
A defective expansion valve can manifest itself as follows:
There are a number of possible causes of failure:
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Professional Auto Care is an award-winning family owned and operated auto repair shop located in southwest Houston. It has been run by the same family, the Serratos Family, for nearly 35 years. Professional Auto Care services Domestic, Asian as well as select European vehicles. We are known for our professionalism, transparency and quality of work. Since our humble beginning in 1983, we always strove to provide the best, most reliable service in Houston with a hint of the personal touch. The founders, Everardo and Claudia Serratos, are still involved with the daily operations of the car maintenance and auto repair shop. Schedule Service online or speak to one of our ASE Certified Service Consultants about your automotive service needs today. (713) 270-0474 |