How to Clean an Expansion Valve (TXV)?

The Thermal Expansion Valve (TXV) is an essential device in the refrigeration and HVAC industry. This valve is involved in controlling the amount of refrigerant liquid released into the evaporator section. Thus, it indirectly affects maintaining extremely low and high temperatures.

Sometimes, the TXV can cause issues in its functioning and requires cleaning or replacement. In this article, we’ll guide technicians on how to clean Expansion Valves.

Keep in mind that TXV's are relatively cheap parts, and cleaning should only be considered an option when it isn't feasible to get a replacement.

TXV measures the amount of superheat at the end of the outlet and increases or decreases the refrigerant liquid flowing through the evaporator to maintain a constant state of superheat.

Procedure to Clean Thermal Expansion Valve (TXV)

If a malfunctioning valve is detected, technicians should follow these steps to clean the defective TVX.

1. First of all, remove the system charge. Then put the charge into the condensing unit in case the shut-off is connected to the unit. Be careful so that the refrigerants do not spill out or disperse in the environment.
2. Remove the cap from the nut at the bottom of the valve for a detailed cross-section view of the inner side. After that, cut out the liquid line present outside of the coil cabinet. 
3. After cutting, apply pressure to the feed tube with the help of rubber or plastic hose, which must pass through the middle of the valve body to remove any extra debris, particles, and oxides. Pressure should be applied for a long enough time and along with the cut.
4. Apply the pressure in the opposite direction at the valve to ensure that the passage is completely clean and there are no debris and particles in the cut.
5. After assuring that the cap, needle, and spring are completely clean, re-join the valve.
6. Then introduce a fluid line channel filter/drier and a sight glass where the valve was cut.  The sight glass is supposed to be present downstream of the filter/drier. On the off chance that the system is heat-pump-based, don’t forget to utilize a filter/drier specific to heat-pump type and is especially designed to deal with refrigerant streams in both directions.
7. Check all connections carefully if there is any leakage left to repair.
8. Now This is the final step; an evacuation of the system is mandatory. To check evacuation, the triple evacuation method is highly recommended. There will be chances of formation of ice when evacuating.

The sudden pressure drop that can happen during expansion can cause severe damage to the refrigerant system. When it passes through the evaporator, it heats the system. Thus, for the system to work normally, TVX must control the liquid flow of the refrigerant.

How Do I Know If My Expansion Valve is Clogged?

There are signs in the performance of the HVAC system if the valve is clogged and not performing well:

• The refrigerant system is cooling slowly and, in some cases, no cooling at all.
• The refrigerant system is performing worse and blowing hot air out despite cool air. Hot air is the first sign that the refrigerant system is problematic somewhere.
• The refrigerant is not working well, but the compressor of the refrigerant is constantly running.
• The system rapidly turns On and then turns OFF.
• The refrigerant is blowing frosty air from vents.