Auto Car Thermal Expansion Valves

The auto ac expansion valve of the automotive air conditioner is installed at the entrance of the evaporator, and has two main functions.

Throttle effect. After the high temperature and high pressure liquid refrigerant is throttled through the orifice of the auto ac expansion valve, it becomes a low temperature and low pressure mist refrigerant, which creates conditions for the evaporation of the refrigerant.

Control the flow of refrigerant. The liquid refrigerant entering the evaporator, after passing through the evaporator, the refrigerant evaporates from liquid to gaseous state, absorbs heat, and reduces the temperature inside the car. The car ac expansion valve controls the flow of refrigerant to ensure that the outlet of the evaporator is completely gaseous refrigerant. If the flow rate is too large, the outlet contains liquid refrigerant, which may enter the compressor and cause liquid shock. If the flow rate is too small, the evaporation will be completed in advance, resulting in insufficient cooling.

Key Features of A/C Expansion Valves

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Advanced structure of a dual-flow balanced orifice.

Stable superheat degree to make the system run stably.

Dual-flow thermal expansion valve saves the number of expansion valves, check valves and solenoid valves in the refrigeration system.

Suitable for various working needs such as refrigeration and air conditioning.

Two-way balanced flow port makes the static superheat change with the change of the condensing pressure or the pressure drop through the valve port.

Evaporation temperature range: -40℃ to +10℃.

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Suitable for R12, R22, R134a and other media.

How To Test Car AC Expansion Valve?

Connect the car ac thermal expansion valve to the high pressure side and the low pressure side of the branch pressure gauge according to the high pressure and low pressure, then connect the intermediate hose to the injection valve and inject the refrigerant. Take a water tank, put the capillary of the car expansion valve into it, observe the water temperature in the water tank and the pressure of the high pressure gauge, operate the high pressure manual network, make the pointer of the high pressure gauge reach 490kpa, and the refrigerant will be discharged from the car expansion valve in a gaseous state. If the intersection of the water temperature and the high pressure gauge pressure is between the two curves, the car expansion valve is ok.

The auto ac expansion valve is actually a pressure reducing valve, and the flow rate determines the cooling effect. Therefore, its opening size is strictly controlled. In general, blockage is the most common failure. If it is blocked, the pressure gauge will find that the high pressure is too high and the low pressure is too low. If the opening is too large, the high pressure is low and the low pressure is high. The standard amount of refrigerant, when the engine is idling, the air pressure of the car should be 0.1 ~ 0.25 MPa. If the low pressure is lower than or higher than this range, it means that the opening of the expansion valve is not good.

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