How To Check Superheat On A Walk In Freezer. Don't use an infrared thermometer for this task. Usually the bottom rows of the evaporator will freeze up when this occurs.
Then take the suction pressure and convert it to temperature on a temperature/pressure chart. Check any suspect areas with an electronic leak detector. There is no external superheat adjustment on those.
Set the superheat around 6 to 8 degrees in the freezers and around 8 to 10 degrees in the coolers.
Excessive or high superheat is an indication of insufficient refrigerant in the evaporator coil for the heat load present. The valve itself may also need to be replaced, but the easiest check would be the inlet screen. Subtract the two numbers to get superheat. Check compressor and evaporator superheat, adjust if necessary.