I’m not Charley, but it’s still a TXV or Thermostatic Expansion Valve. It changes the high pressure liquid refrigerant into a low pressure vapor by a variable restriction. Turn a can of air (computer duster) upside down - it’s exactly the same thing.
It throttles based on the measured superheat at the end of the evaporator coil. That’s what the capillary tube is for - the temperature bulb.
Sounds like the system was low on refrigerant, but there are other causes as well.