A starved coil shows high superheat, low suction pressure and only the first few passes cold to the touch. Causes include low charge, a restricted drier or metering device, a TXV with a lost bulb charge or plugged screen, or flash gas in the liquid line. Capacity drops, and the compressor runs hot because the suction gas that cools it is too warm and too thin.
Coil's starved, only the bottom third is sweating and superheat is 30, check subcooling to see if it's charge or restriction.
Also heard as
- starving
- underfed
Do not mix it up with
- Floodback: A starved coil gets too little refrigerant and shows high superheat; floodback is too much refrigerant and near-zero superheat.
Related terms
Superheat
How many degrees refrigerant vapor is above its boiling point at the pressure it is at.
Flash gas
Liquid refrigerant that turns to vapor because its pressure dropped, either at the metering device or where it shouldn't.
Metering device
The restriction that drops refrigerant from high side to low side pressure and controls how much enters the evaporator.
TXV
Thermostatic expansion valve: a metering device that adjusts refrigerant flow to hold constant evaporator superheat.