How to Use a Manifold Set for R22

Manifold sets are used to check the charge of an HVAC unit. R-22 is a common refrigerant used in home air conditioning units, although it has been phased out in newer units. R-22 manifold sets read the pressure and temperature of HVAC units with R-502, R-22 or R-12 refrigerant. However, R-22 manifolds will not work with other types of refrigerant, because the higher pressures will not read accurately and may damage the manifold hoses. While checking the charge on your unit using a manifold set is fairly simple, only a licensed professional should attempt to recharge the unit with R-22.

R-22 manifold set

Instructions

- 1
  Look at the manifold set. You will see it is color-coded. The low pressure gauge, also called the compound gauge, has a blue hose. The high pressure hose is red. Turn the manifold so that the blue hose is on your left and the red is on your right. Some HVAC systems also color-code the hand valves on the unit, to help guide you through the process.
- 2
  Locate the ports on the outdoor unit. Screw the blue hose's nozzle onto the port on the air conditioner suction line. This is the compound gauge, which measures atmospheric pressure and vacuum pressure. Connect the red hose's nozzle to the port on the air conditioner unit discharge line or liquid line. Screw down to tighten.
- 3
  Open the hand valves. Look at the pressures and the temperature on the compound gauge. Sometimes the compound gauge may not list the temperatures, only the pressure. A chart may be necessary to determine the accurate temperature according to the gauge. This chart is typically included with the manifold set.
- 4
  Compare these measurements with the recommended pressures from your HVAC manufacturer, to ensure your unit is properly charged.
- 5
  Close the hand valves, and unscrew the manifold set.

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