Troubleshooting Failed Thermal Expansion Valve

We have been hearing some chatter regarding new coils with bad thermal expansion valves (TXVs). There are usually two reasons the valves appear not to be operating properly.

  • Make sure that the suction service valve on the condensing unit is opened first. This will fill the lineset and system with vapor refrigerant. If the liquid line service valve is opened first, it causes liquid refrigerant and oil to rush to the valve inlet. If there is a column of oil at the inlet of the valve it will appear that the valve is not functioning because the valve cannot meter properly with a column of oil on the inlet.

  • Another tip is to remove the sensing bulb off of the suction line and warm it either in your hand or warm water. This will cause the valve to open and allow refrigerant and oil through the valve. A new valve has no lubrication in it and may stick on startup, until we move refrigerant and oil through the valve to help lubricate all of the internal parts of the valve.

These practices should cut down on some of the alleged TXV failures, but if you continue to have issues, reach out to our Customer Assurance team.

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