Thermostatic expansion valve. A sensing bulb clamped to the suction line at the evaporator outlet pushes on a diaphragm through a capillary; if superheat rises, the valve opens to feed more refrigerant, and if it falls, the valve closes. Typical settings hold about 8 to 12 degrees F of superheat. A loose or uninsulated bulb, a plugged inlet screen or a lost bulb charge are the common faults.
TXV bulb was just hanging by the zip tie, no wonder it's flooding, strap it tight and insulate it.
On suction lines 7/8 inch and smaller, mount the bulb on top; on larger lines, at 4 or 8 o'clock, never on the bottom where oil runs.
Also heard as
- TEV
- TX valve
- thermostatic expansion valve
Related terms
Metering device
The restriction that drops refrigerant from high side to low side pressure and controls how much enters the evaporator.
Superheat
How many degrees refrigerant vapor is above its boiling point at the pressure it is at.
Hunting
A TXV or control swinging back and forth, alternately overfeeding and starving the evaporator instead of settling.
Subcooling
How many degrees liquid refrigerant is below its condensing temperature at the same pressure.