How to Use Refrigerant Gauges
- 1). Shut off the refrigeration system. Connect the refrigerant gauges to your system at the low and high pressure service connections. Connect the blue hose to the low pressure side or evaporator. Connect the red hose to the high pressure side or condenser.
- 2). Turn on the refrigeration system and allow it to reach steady operation. Open the low side gauge valve and read the pressure on the gauge. Convert the pressure reading on the gauge to a temperature by using the pressure/temperature chart for the refrigerant in the system. Close this valve and open the high side gauge valve. Read the pressure for the high side and convert the pressure to temperature for the condenser. Use these temperatures to determine the operating temperatures of the low side evaporator and the high side condenser.
- 3). Close both valves before connecting the yellow or utility hose to a refrigerant supply cylinder or a vacuum pump. Add liquid refrigerant when charging a refrigeration system. Connect the utility hose to a vacuum pump and open the low side valve to evacuate refrigerant from the system. Monitor the vacuum using the vacuum readings on the low side gauge.
- 4). Replace the service valve caps when done to prevent refrigerant leaking or moisture entering the system.