An R22 pressure chart shows the saturation pressure of R-22 at each temperature. Technicians use it to turn a gauge reading into a saturation temperature, then use that number to check superheat, subcooling, and overall system health. R-22 still runs in many homes and light commercial buildings installed before 2010, even though US production and import ended in 2020.

This guide from Royal Refrigerants gives you a full R22 PT chart, explains high-side, low-side, and standing pressure, and shows how to use the numbers when troubleshooting.

R22 PT Chart (Pressure Temperature Chart in PSIG)

The values below are saturation pressures in PSIG at sea level, calculated from standard R-22 thermodynamic property data. They are not target running pressures.

Compare manufacturer charts before critical work, as small differences in rounding are normal.

How to Read an R22 PT Chart

R-22 boils and condenses at a fixed temperature for each pressure. That point is called saturation.

• Pressure to temperature: Read the gauge, find that pressure in the chart, and read across to the temperature. A suction reading of 68.6 PSIG means the refrigerant in the evaporator is boiling at about 40°F.

• Temperature to pressure: Start with a known temperature to find the matching pressure. At 70°F, R-22 saturation pressure is 121.4 PSIG. At 85°F it is 155.7 PSIG, and at 100°F it is 195.9 PSIG.

• PSIG vs PSIA: Gauges read PSIG, pressure above the surrounding air. PSIA adds about 14.7 psi of atmospheric pressure at sea level. HVAC charts use PSIG.

• Fahrenheit vs Celsius: The chart lists both, so you can work in either unit.

These are saturation values only. They do not tell you what a running system should read, because load, airflow, and charge all shift the numbers. If you also service newer equipment, keep an R-410A pressure chart on hand, since R-410A runs at much higher pressures.

R22 Pressure Chart: High Side and Low Side

What Is R22 Low-Side Pressure?

Low-side pressure, or suction pressure, is read at the larger suction line between the evaporator and compressor. Inside the evaporator, R-22 boils as it absorbs heat from indoor air. The suction pressure tells you the evaporator saturation temperature. Indoor heat load, evaporator airflow, filter condition, metering device, and refrigerant charge all affect it.

What Is R22 High-Side Pressure?

High-side pressure, or head pressure, is read at the smaller liquid line. In the condenser, hot R-22 vapor gives off heat outdoors and turns back to liquid. The high-side pressure tells you the condensing saturation temperature. On most air-cooled units, that runs roughly 20 to 30°F above outdoor temperature, so head pressure rises on hot days and drops when the condenser coil is clean and airflow is strong.

Typical R22 Operating Pressure Reference

Treat these as rough guides, not specifications. Real R22 running pressures depend on the equipment, indoor and outdoor temperatures, airflow, charge, and load. Always check the manufacturer's charging chart.

R22 Standing Pressure Chart

What Is R22 Standing Pressure?

Standing pressure, or static pressure, is the reading with the system off. Once the compressor stops, pressure equalizes between the high and low sides. If liquid and vapor are both present, the pressure matches the saturation pressure at the refrigerant's temperature.

How Temperature Affects R22 Standing Pressure

If an R-22 system has been off long enough to reach 85°F all the way through, standing pressure should read close to 155.7 PSIG. At 70°F it should be near 121.4 PSIG, and at 95°F near 181.8 PSIG. Parts sitting in sun or shade can be at different temperatures, so give the system time to settle.

Standing pressure confirms that some liquid refrigerant is present and can flag non-condensable gases if the reading is far above the chart value. It cannot tell you if the charge is correct. A system missing a third of its charge can still show normal standing pressure.

R22 Pressure at Different Outdoor Temperatures

Outdoor temperature mainly drives head pressure, while indoor load mainly drives suction pressure.

Outdoor air temperature and refrigerant saturation temperature are different numbers. Use the PT chart to convert pressure into saturation temperature before you compare it with the air around the coil.

R22 Saturation Pressure and Temperature Explained

At saturation, liquid and vapor R-22 exist together, and pressure and temperature are locked to each other. Raise the pressure and the boiling point rises. Lower it and the boiling point falls. That is why the evaporator runs at low pressure to boil cold, and the condenser runs at high pressure to condense hot. Running pressure is a measured number, while saturation pressure is a property of the gas. Technicians link the two through the PT chart to calculate superheat and subcooling.

How to Calculate R22 Superheat

Superheat is how many degrees the suction vapor has warmed above its boiling point. It shows whether the evaporator is getting the right amount of refrigerant. Measure suction-line temperature near the outdoor unit with a clamp thermometer.

Superheat = actual suction line temperature minus evaporator saturation temperature

Example: suction pressure reads 68.6 PSIG, which the R22 PT chart converts to 40°F. The suction line measures 50°F. Superheat is 50 minus 40, or 10°F. Compare that with the manufacturer's target superheat for the indoor and outdoor conditions, since fixed-orifice systems use a chart.

How to Calculate R22 Subcooling

Subcooling is how many degrees the liquid has cooled below its condensing temperature. It shows how well the condenser is doing its job, and it is the main charging check on systems with a TXV. Measure liquid-line temperature near the service valve.

Subcooling = condensing saturation temperature minus actual liquid line temperature

Example: head pressure reads 226.4 PSIG, which equals 110°F on the chart. The liquid line measures 100°F. Subcooling is 110 minus 100, or 10°F. Most TXV systems target somewhere around 8 to 12°F, but the equipment data plate or manual sets the real number.

What Causes Low R22 Suction Pressure?

• Low refrigerant charge from a leak

• Restricted metering device or TXV

• Dirty air filter or blocked return

• Low evaporator airflow from a weak blower or dirty coil

• Low indoor heat load on a mild day

• Kinked or restricted refrigerant lines

Low suction pressure alone does not tell you which one it is. Check superheat, subcooling, and airflow together. A low charge usually shows high superheat and low subcooling, while a restriction often shows high superheat with normal or high subcooling. If the cause is a leak, find and repair it before adding R-22 refrigerant. Our guide to common causes of HVAC refrigerant leaks covers where to look.

What Causes High R22 Head Pressure?

• Dirty condenser coil

• Poor condenser airflow or a failed fan motor

• Overcharge

• Non-condensable gases such as air in the system

• Very high outdoor temperature

• Restrictions in the condenser

Measure outdoor air temperature, convert head pressure to condensing temperature, and compare the difference. A large gap points to airflow or coil problems. High head pressure with high subcooling often means an overcharge, one of the most common refrigerant charging mistakes.

R22 Pressure Chart PDF Download

Download the printable R22 pressure chart PDF to keep in your truck or service binder. It lists R-22 saturation pressure in PSIG from -40°F to 130°F with Celsius values, and it notes that every value is a saturation pressure, not a target running pressure.

Retrofit and Replacement Options for R-22 Systems

Because R-22 now comes only from reclaimed or stockpiled supply, the R22 Freon cost per pound stays high. For older systems with a major leak, many contractors retrofit with R407C refrigerant, which needs a full recovery and usually an oil change. Compare all options in our guide to the substitute for Freon R22. When a system is replaced, new equipment runs on R454B refrigerant or R32 refrigerant, and neither can go into an R-22 system.

Frequently Asked Questions

What pressure does R22 run at? 

On a typical summer day, often around 60 to 75 PSIG on the low side and 200 to 250 PSIG on the high side. Actual readings depend on conditions and equipment.

What are good pressures for R22? 

Good pressures are the ones that give correct superheat or subcooling for the conditions, based on the manufacturer's chart.

What is the normal R22 low-side pressure? 

Roughly 60 to 75 PSIG, matching an evaporator temperature of about 35 to 44°F.

What is the normal R22 high-side pressure? 

Roughly 200 to 250 PSIG in normal summer weather, and higher in extreme heat.

What is R22 standing pressure at 85°F? 

About 155.7 PSIG.

What is R22 pressure at 70°F? 

About 121.4 PSIG at saturation.

How do I read an R22 PT chart? 

Find your gauge pressure in the chart and read across to the saturation temperature, or the reverse.

What is the difference between PSIG and PSIA? 

PSIG is gauge pressure. PSIA adds about 14.7 psi of atmospheric pressure.

How does outdoor temperature affect R22 pressure? 

Higher outdoor temperature raises head pressure, and to a smaller degree suction pressure.

What causes low R22 suction pressure? 

Low charge, restrictions, low airflow, a dirty filter, or low indoor load.

What causes high R22 head pressure? 

A dirty condenser, poor airflow, overcharge, air in the system, or extreme heat.

Where can I download an R22 pressure chart PDF? 

Use the printable PDF in the download section above.

Conclusion

An accurate R22 pressure chart is the starting point for every R-22 diagnosis. Keep saturation, running, and standing pressure separate in your head, and always pair pressure readings with superheat, subcooling, airflow, and outdoor conditions. Follow the equipment maker's charging data, and when an aging R-22 system needs refrigerant or replacement, Royal Refrigerants can help with retrofit refrigerants and low-GWP cylinders for new equipment.