How to Add Freon to Rheem Air Conditioners

Turn the Rheem air conditioning system on at the thermostat. Move the temperature setting to its lowest level. Check the inside temperature with the thermostat's thermometer.

Open both of the brass refrigerant service valve caps with an adjustable wrench. The service valves, located on the outside unit where the copper refrigerant lines enter the Rheem condensing unit, provide access to the refrigerant's closed system. The caps screw onto the high- and low-pressure refrigerant service valves.

Put on leather work gloves. Escaping high-pressure refrigerant will cause frostbite to bare skin when connecting the manifold gauges.

Screw the middle hose of a refrigerant manifold gauge to a jug of Freon or another brand of refrigerant. Refrigerant manifold gauges have three hoses connected to a brass manifold. Two gauges also connect to the manifold. A handle on each side of the manifold operates a set of valves inside of the manifold. One handle operates the high-pressure side, and one operates the low-pressure side.

Purge the middle hose. Open the jug of refrigerant. Open one of the manifold's valve handles for two seconds.

Screw the manifold's left hose to the large refrigerant line's service valve. The left hose operates the low-pressure manifold valve and gauge.

Screw the manifold's right hose to the small refrigerant line's service valve. The right hose operates the high-pressure manifold valve and gauge.

Open the Rheem condensing unit's service panel with a nut driver. The service panel, found above the refrigerant lines, has a temperature/pressure chart stuck to the inside.

Use the chart to find the correct refrigerant pressure for the inside air temperature using the pressure/temperature chart. Follow the "Temperature" row until the number corresponds with the inside air temperature. Find the proper refrigerant pressure for that temperature. Add refrigerant if the gauge reads a low pressure.

Open the manifold's left valve handle for 60 seconds. Close the handle and allow the gauge's needle to settle. Compare the new gauge reading to the temperature/pressure chart. Continue to add refrigerant until the gauge reads within five pounds per square inch (psi) of the ideal pressure level. Dirty coils and filters or improper air flow will have slight effects on the pressure reading.

Check the outside temperature with a thermometer. Compare this reading and the high-pressure manifold gauge reading to the pressure/temperature chart. Service technicians use this information to determine the total health of the refrigerant system, checking the compressor and heat exchanger. Extreme differences require system maintenance and/or repair.

Turn the refrigerant jug's valve off.

Unscrew the manifold's hoses from both service valves and the refrigerant jug.

Replace the service valve caps and the condenser's service panel.