Thermal Expansion Valves For Vehicle A/C
Thermal expansion valves are important components of the air conditioning system that control how much refrigerant enters the evaporator. If it fails, it no longer regulates the air conditioner temperature, and the interior of your vehicle may heat up.
Replacing the thermal expansion valve promptly when it fails can save you expensive repairs on your car’s air conditioning system. If not replaced quickly, liquid may enter the compressor and cause internal damage, requiring replacement of major air conditioner components.
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- How does the thermal expansion valve work?
The thermal expansion valve removes pressure from the liquid refrigerant to allow it to expand to become a gas in the evaporator. As the liquid refrigerant leaves the TX valve the refrigerant is at its coldest.
The thermal expansion valve is designed so that the refrigerant at the evaporator outlet must reach a temperature of 4-7°C before more refrigerant is allowed to enter the evaporator. The ‘superheat spring’ inside the expansion valve has a tension that determines when the valve opens and closes to control the amount of refrigerant entering the evaporator as the temperature fluctuates.
- What are the symptoms of a faulty thermal expansion valve?
The first sign that there’s a problem with the thermal expansion valve is that the air conditioner blows warm instead of cool air. This indicates that not enough refrigerant is entering the system.
If the air blows too cold or the evaporator frosts over, this also indicates a faulty thermal expansion valve.
- How much does a thermal expansion valve cost?
The price of a replacement TX valve varies depending on the model of vehicle. The cost can increase when other maintenance needs to be done on your air conditioner at the same time,
For example, it is best practice to flush the air conditioning system when new parts are installed. The expansion valve is controlled by a temperature sensor, if this is blamed for the TX valve failure, it may need to be replaced. The evaporator or receiver drier may also need replacing to ensure healthy functioning of the air conditioning system.
Make sure that you get a quote for labour costs when you ask about thermal expansion valve replacement.
- Where is the thermal expansion valve?
The thermal expansion valve (which might otherwise be referred to as the thermostatic expansion valve or the tx valve) can be found in most refrigeration systems. It is located immediately in front of the evaporator.
- What are the components of a thermal expansion valve?
Thermal expansion valves vary in kind and design, but the underlying principle components are the same. These are:
- Valve body: holds the components inside and has a hole that restricts the flow of refrigerant
- Diaphragm: a strong, flexible piece of material (usually metal) that puts pressure on the needle
- Needle: moves to change the size of the opening and the flow of refrigerant
- Spring: acts as a counter to the needle
- Sensing bulb: measures the temperature of the refrigerant at the exit
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