Determine the following data: (They can be found on the unit nameplate).
1. Btu or tonnage rating of the unit
2. System refrigerant
3. Evaporator temperature or pressure (Determine the expected evaporator temperature.)
4. High-side temperature (or pressure)
5. Pressure drop across the valve
These valves are set at a predetermined pressure and sealed with a lock nut. Loosen nut to readjust. Heat the screw with a heat gun to loosen for readjustment.
For servicing AEVs, see the double-temperature valve pages.