Formula
Subcool = Sat Temp (from P/T) − Measured Liquid Line TempPick the refrigerant; sat temp is looked up from its PT chart. Target subcool is on the equipment data plate (typ. 8–12°F).
Saturation temp
83.8°F
R-410A @ 250 psig
Actual subcool
-11.2°F
Target 10°F · -21.2°F vs. target
Undercharged — low subcool means refrigerant flashing in liquid line. Find leak before adding. Negative subcool = no liquid at metering device. Check charge immediately.