[Bradical]

Submerge the sensing bulb in ice water while the system is running and it should close right up. If the gas in the bulb/power head is lost, which is a completely closed, non serviceable independent charge, the TXV will fail closed. There is an inlet screen that will prevent debris that somehow may have made it past the drier from entering the valve assembly and result in a fully closed symptom as well. The only opening force for the TXV is the pressure from high temperature building up in the bulb and forcing down on the diaphragm to open it, hence why I say they don't fail open.