What causes a thermal expansion valve to fail?
A TXV valve can fail if it’s too open and overfeeding or too closed (underfeeding). Contaminants from a dirty evaporator coil, oil, or moisture can cause the valve to get “sticky”. In addition, a blocked return air vent can cause a TXV valve to go bad.
What happens when expansion valve sticks closed?
If the expansion valve is stuck open or clogged, the A/C system will not cool properly. A clogged valve will increase the pressure in the system and cause the A/C compressor to overheat. If the valve is stuck open, too much refrigerant is allowed to pass through the system and into the compressor.
What are the symptoms of a stuck expansion valve?
One common symptom of a stuck expansion valve is when the air conditioning unit starts to run continuously, even when the car isn’t being driven. This usually indicates that there is something blocking the flow of refrigerant which is causing the expansion valve to remain open.
How does electronic expansion valve works?
The electronic expansion valve (EEV) operates with a much more sophisticated design. EEVs control the flow of refrigerant entering a direct expansion evaporator. They do this in response to signals sent to them by an electronic controller. A small motor is used to open and close the valve port.
Can expansion valve leak?
The expansion valve can also malfunction due to a problem with the compressor. If the compressor fails, it will not be able to send enough refrigerant to the expansion device, and this will cause pressure problems which can lead to a valve leak.
What would indicate that your expansion valve is leaking?
Inconsistent Air Flow If you hear a “chugging” sound as the revs drop then rise again, that may indicate that your expansion valve has failed. If there are no obvious sounds coming from the engine bay, you can get an idea of whether or not your valve is bad by checking the ac system for leaks.
Can expansion valve be adjusted?
The TXV cannot be adjusted open or closed, it is a modulating valve. Turning the adjustment stem clockwise will only increase spring pressure causing a higher superheat.