1. Attach suction and discharge pressure gauges.
2. Operate the unit in high speed cool.
3. Note the ambient (outside air) and box temperatures.
4. Follow the formulas below to find approximate normal suction and discharge pressures for the unit.
5. Compare the calculated normal pressures to the actual and the follow the conditions on the next page.
Discharge Pressure Formula
a. Ambient air temperature plus 30 F (16.6 C) = approximate condenser temperature.
b. Convert condenser temperature to pressure using the Pressure Temperature Chart.
Suction Pressure Formula
a. Box temperature minus 15 F (8.3 C) = approximate evaporator temperature.
b. Convert evaporator temperature to pressure using the Pressure Temperature Chart.
NOTE: Pressure Temperature Chart located at the rear of the book.