Low-Side R-22 Pressure at 75 Degrees F

During normal operation, low-side pressure during R-22 operation is about 75 psi. This depends on indoor wet bulb temperature and outdoor ambient heat load.

The vapor line pressure varies by the incoming or suction line temperature and the compressor model and refrigerant used. It’s best to use a temperature correction chart for R-22 and any other refrigerant gas and the actual room or ambient temperature.

High Side

A good way to tell if you are seeing the right pressure on the high side of your air conditioner is by looking at a temperature chart. This chart will tell you how much psi the high side pressure should be at different temperatures.

R22 pressure at 75 degrees is about 135 psi, which should be about right for an air conditioning system. This number will vary by ambient temperature and compressor model.

To figure out the evaporating temperature of R22 (or any other refrigerant) add 15 to 25 degrees F to the outdoor temperature. For example, with an 85 degree outdoor temperature, the evaporating temperature of R22 should be between 90 and 115 degrees F.

The suction pressure depends on the TEMPERATURE at which R22 boils in the evaporator coil, which is about 35 to 40 degrees F below the return air temperature. For example, if the return air temperature is 75 degrees, then the evaporating temperature of R22 is about 105 to 115 degrees.

Low Side

The low side of the refrigerant pressure is dependent on the temperature of the boiling (evaporating) refrigerant. The evaporating temperature should be about 35 to 40 degrees F below the return air temperature.

When you connect a gauge to the low side, it should read less than 100 psi. This is a common measurement in refrigerant pressure charts.

In addition, the high side of the gauge should point to a temperature between 105 and 115 degrees (in the green ring). The high side pressure is also read on the black ring of numbers for pressure.

When the compressor is turned off for 30 minutes or so, the high and low side pressures equalize throughout the system. This is important to ensure the refrigerant gas stays at a consistent temperature throughout the system.

Evaporator Coil

The evaporator coil is the part of your air conditioner that absorbs heat from the air inside of your home. It’s also the part that dehumidifies your indoor air by collecting moisture in the form of condensation on its fins.

Your evaporator coil is made up of U-shaped metal tubes that easily conduct the heat from the refrigerant that circulates through it. These metal tubes can rust, though.

If you notice any signs of corrosion on your evaporator coil, get in touch with a licensed HVAC technician right away. They can diagnose the problem and offer solutions.

The evaporator coil of r22 pressure at 75 degrees is a vital component in your air conditioning system, and it’s important to care for it properly. Dirty evaporator coils can cause your unit to malfunction and cost you money in the long run.


The compressor coil of an air conditioning system is where the refrigerant gas is compressed to a high pressure before it is discharged from the evaporator into the ambient room. This process is done by the motorized compressor and the evaporator coil.

The incoming or suction line pressure during normal operation of an R22 compressor, using the service chart for that model and refrigerant, is about 75 psi when the air temperature outside the building is 85 degrees Fahrenheit. The output or high-side pressure for this same compressor model and refrigerant is 260 psi.

With a temperature correction chart one can read the static or equalized refrigerant pressure of any gas and the actual ambient temperature of the indoor or outdoor space. This information is not available from pressure test gauges, which only measure the refrigerant pressure in a static or equalized air conditioning or heat pump system.

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