R-410A PT Chart

R-410A was the standard refrigerant in US central air-conditioners and heat pumps until new systems moved to R-32 and R-454B in 2025. This chart gives its liquid and vapor pressures at every whole degree from -40 to 150 °F, checked against Arkema and Daikin tables.

How to read an R-410A PT chart

A pressure-temperature (PT) chart gives the pressure at which a refrigerant boils or condenses at each temperature: its saturation pressure. Where liquid and vapor are both present, as in an evaporator, a condenser or a cylinder, the pressure and the temperature are tied together, so a gauge reading tells you the temperature the refrigerant is boiling or condensing at.

R-410A is a blend, and a blend boils over a range of temperatures rather than at one. So the chart has two columns. The liquid (bubble point) pressure is where the first bubble of vapor forms; the vapor (dew point) pressure is where the last drop of liquid boils away. At the same pressure, the two temperatures differ by 0.2 °F for R-410A (the temperature glide, at the 40 °F dew-point pressure).

The pressures are gauge pressure (psig) at sea level. Below 0 psig the refrigerant is under vacuum, and the chart shows inches of mercury instead. Switch the units above to °C, kPa or bar, and type any temperature or pressure into the lookup for a value between the rows.

Superheat and subcooling: a worked example

The lookup above does both calculations. Here is what it does, with example readings. They show the method only; they are not target pressures for any system.

Whether a superheat or subcooling figure is right for a system depends on that system. Compare with the manufacturer’s charging instructions.

How far off a reading can be

Superheat and subcooling are differences of a few degrees, so a small error in the pressure shows up in the answer. This table works out, from the R-410A chart itself, how far each common mistake moves the result.

Worked out from this chart. For R-410A, 1 °F is about 2.3 psi at a 40 °F suction and 4.5 psi at a 100 °F liquid line. At 5,000 ft a gauge reads 2.5 psi lower than at sea level for the same refrigerant pressure.

Gauge pressure and elevation

A gauge reads the difference between the refrigerant’s pressure and the air around it. Air pressure falls with height, so at the same temperature a gauge reads higher up a mountain than at sea level. At 40 °F, R-410A vapor reads 118.4 psig at sea level and 120.8 psig at 5,000 ft, where standard air pressure is 12.23 psia.

Enter your elevation in the lookup and the whole chart, CSV and printout switch to it. The tool uses the standard atmosphere, which is what Arkema’s 5,000 ft chart uses; our values match that chart to within 0.15 psi. Weather moves air pressure too, by much less.

About R-410A

Boiling point at 1 atm (bubble)

-60.6 °F (-51.4 °C)

Critical temperature

160.4 °F (71.3 °C)

Critical pressure

710.9 psia (4,901 kPa)

Temperature glide

0.2 °F at the 40 °F dew-point pressure

Boiling point, critical point and glide are computed from the same equation of state as the chart. GWP is from our refrigerant GWP dataset; the refrigerant leakage calculator turns a leak into CO₂e.

Since 1 January 2025, new US residential and light-commercial air-conditioners and heat pumps must use a refrigerant with a global warming potential below 700, and R-410A is above it. Existing R-410A systems can still be serviced. Our R-410A, R-32 and R-454B section gives the dates and the rules they come from.

How we checked these numbers

Every value is computed with CoolProp 8.0.0 from the reference equation of state for R-410A (Lemmon (2003), International Journal of Thermophysics 24(4), pseudo-pure model), as absolute pressure, then converted to gauge. Before publishing, we compared it with every independent table we could find:

Gauge pressure at 5,000 ft: our absolute pressure less standard-atmosphere air pressure there (12.23 psia).

Checked 28 Oct 2026. A chart printed to one decimal place rounds by up to 0.05 psi.

The °C table is computed at whole degrees Celsius, not converted from the °F rows, and the two agree to within 0.01 psi.

Questions about the R-410A PT chart

Other refrigerants

• R-22 →Older US air-conditioners and heat pumpsAt 40 °F68.6 psigHCFCA1, no flame propagation
• R-134a →Car air-conditioning, since it replaced R‑12At 40 °F35.0 psigHFCA1, no flame propagation
• R-404A →RefrigerationAt 40 °F86.9 / 85.4 psigHFC blendA1, no flame propagation
• R-454B →New US air-conditioners and heat pumps since 2025At 40 °F112.0 / 107.0 psigHFC/HFO blendA2L, lower flammability
• R-32 →New US air-conditioners and heat pumps since 2025At 40 °F121.0 psigHFCA2L, lower flammability
• R-290 →Propane, used as a refrigerantAt 40 °F63.9 psigHydrocarbonA3, higher flammability
• R-1234yf →Car air-conditioningAt 40 °F38.4 psigHFOA2L, lower flammability
• All 8 compared →Every refrigerant at one temperature, and a side-by-side table from -20 to 120 °F

Pressures are gauge at sea level; for blends, liquid (bubble) / vapor (dew). Safety classes are ASHRAE 34.

Version history

• 1.1.1 (29 October 2026): sources moved into a compact card at the end of the page, so they no longer break up the reading.
• 1.1 (28 October 2026): new section on how far off a reading can be, worked out for this refrigerant, and a note on how closely the published charts agree.
• 1.0.1 (28 October 2026): other refrigerants shown as cards, with each gas’s use, pressure at 40 °F, type and safety class.
• 1.0 (28 October 2026): first published.