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Photograph of a commercial air conditioning compressor charging gauge set (C) InspectAPedia.com R-134A Refrigerant Pressure Charts

R-134A refrigerant charge quantity for air conditioners & heat pumps:

This air conditioning repair article series discusses the the diagnosis and correction of abnormal air conditioner refrigerant line pressures as a means for evaluating the condition of the air conditioner compressor motor, which in turn, is a step in how we evaluate and correct lost or reduced air conditioner cooling capacity.

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HFC Example R-134A Pressure / Temperature Charts

Measuring the refrigerant pressure in air conditioning, heat pump or other refrigerant systems can diagnose a range of operating problems including a refrigerant leak, over charging or under charging.

Refrigerant pressure readings measured at the air conditioning compressor/condenser unit and which are found to be too low on the high pressure side (compressor output) or on the low pressure side (compressor input or suction line) can indicate a problem with the compressor's ability to develop normal operating pressure ranges and thus will affect the cooling capacity of the air conditioning system.

Abnormally high compressor output pressures are possible but less likely.

Example R-134A Refrigerant Temperature vs Pressure Data
Ambient Temperature R134A Vapor Pressure at Sea Level R-134A Low Side Pressure2 R-134A High Side Pressure3
65.71°F (18°C) 65 psig 25-35 psi / 172-241 kPa 135-155 psi / 931-1069 kPa
69.24°F (21°C) 70 psig 35-40 psi / 241-276 kPa 145-160 psi / 1000-1103 kPa
75.86°F (24°C) 80 psig 35-40 psi / 241-310 kPa 150-170 psi / 1034-1172 kPa
90.37°F (32°C) 105 psig 45-55 psi / 310-379 kPa 250-270 psi / 1724-1862 kPa
100.40°F (38°C) 125 psig 50-55 psi / 345-379 kPa 315-325 psi / 2172-2241 kPa
105°F (41°C) 135 psig 50-55 psi / 345-379 kPa 330-335 psi / 2275-2310 kPa
110°F (43°C) 145 psig 50-55 psi / 345-379 kPa 340-345 psi / 2344-2379 kPa

Notes to the table above

Other Properties of R134A Refrigerant

1. Outdoor ambient temperature

2. Typical low pressure or suction side, may vary by equipment and metering controls

3. Typical high side pressure, may vary by equipment

4. These psig readings for R-134A are what you'd expect the pressure of the gas to be in an enclosed container at the temperature given and at steady state.

R-134A Refrigerant Pressure / Temperature Chart & Table Downloads

Correcting R-134a Refrigerant Pressure & Leaks

Refrigerant Pressure & Leak Correction

If you already know your refrigerant pressures are wrong or that you have a refrigerant leak, please see

If your air conditioning or heat pump system has lost its cooling capacity or won't start see

...

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