R-22 PT Chart

About R-22

R-22 is a single-component HCFC refrigerant that was the standard in US residential and light commercial air conditioning and heat pumps for decades. Because it contains chlorine, it depletes ozone, which is why it was phased out under the Clean Air Act.

Plenty of R-22 systems are still running, so techs still meet it on service calls. A single-component refrigerant has no glide: liquid and vapor share one saturation pressure at each temperature, so the chart below has one pressure column.

• Residential split AC and heat pumps built before 2010
• Packaged rooftop units and light commercial AC
• Older commercial refrigeration and process cooling

R-22 Properties

Key facts for identifying R-22 and choosing tools, oil and replacements.

• R-410A PT chart
• R-407C PT chart
• R-422B PT chart

Typical R-22 Operating Pressures

Suction pressure is the vapor (dew) pressure at the evaporator temperature; head pressure is the liquid (bubble) pressure at the condensing temperature. The temperatures are common design points, not charging targets.

• Check R-22 superheat and subcooling

How to Read the R-22 PT Chart

The chart covers -38°F to 150°F. Pressures are gauge pressure (psig), the number your manifold shows; switch to °C and kPa above if you work in metric.

The chart has one pressure column because liquid and vapor share the same saturation pressure at each temperature. Use the same column for superheat (suction side) and subcooling (liquid side).

To read it, find the pressure on your gauge and read across to the saturation temperature, or start from a temperature and read the pressure. The lookup above interpolates between rows for you.

Superheat and Subcooling Formulas

The PT chart turns a gauge pressure into a saturation temperature. Compare that with a line temperature to get superheat or subcooling.

Tsuction

Suction line temperature near the outdoor unit or compressor, °F

Tliquid

Liquid line temperature leaving the condenser, °F

Tsat

Saturation temperature at the gauge pressure, °F

Gauge pressure (psig) is pressure above atmospheric. Below 0 psig, the chart shows vacuum in inches of mercury.

Worked Example: R-22 Superheat and Subcooling

AC cooling, 95°F outdoor: an R-22 system reads 68.6 psig suction with a 50°F suction line, and 242.8 psig on the liquid line with a 105°F liquid line.

1. Saturation temperature at 68.6 psig: 40.0°F.
2. Superheat: 50°F − 40.0°F = 10.0°F.
3. Saturation temperature at 242.8 psig: 115.0°F.
4. Subcooling: 115.0°F − 105°F = 10.0°F.

Result: 10.0°F superheat and 10.0°F subcooling. Compare them with the manufacturer’s targets before adding or recovering refrigerant.

Is R-22 Being Phased Out?

R-22 is phased out. US production and import ended on January 1, 2020. Owners can keep running existing systems, and service relies on recovered, reclaimed and stockpiled R-22, so prices stay high.

New equipment uses R-410A or, since 2025, low-GWP refrigerants such as R-454B and R-32. When an R-22 system needs a major repair, the usual choices are replacing it or retrofitting it to an HFC blend such as R-407C or R-422B.

R-22 Field Tips

Practical points for working on R-22 systems, from the sources below.

1. 1

   Recover, don’t top off blindly

   Every pound of R-22 is reclaimed or stockpiled supply. Find and fix the leak before adding refrigerant; topping off a leaking system costs the customer more each season.

2. 2

   Weigh the retrofit against replacement

   A retrofit adds labor for oil changes, filter driers and TXV adjustment, and the HFC blends lose some capacity. On an old system with a failed compressor or coil, replacement usually makes more sense.

3. 3

   Label the system after a retrofit

   Tag the unit with the new refrigerant and oil so the next tech does not add R-22 to an R-422B or R-407C system. Mixed refrigerants cannot be reclaimed and must be destroyed.

Sources: EPA: Residential air conditioning and the phaseout of HCFC-22, EPA: Choosing the right R-22 retrofit, ACHR News: R-22 retrofit round-up