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R-407C PT Chart (407C Pressure Temperature)

Look up R-407C liquid and vapor saturation pressures for a temperature, or the temperatures for a gauge reading.

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This R-407C PT chart (407C PT chart) lists the liquid and vapor saturation pressures of R-407C at every temperature. The R-407C PT chart calculator converts between pressure and saturation temperature for R-407C and shows the full pressure-temperature table for this refrigerant. R-407C is an HFC blend used as a replacement for R-22 in air conditioning, so it has separate liquid (bubble) and vapor (dew) pressure values. The tool runs in your browser, is free, and needs no sign-up. Nothing you enter is uploaded. You can view results in °F and psig, °C and bar (gauge), or °C and kPa (gauge), then copy, print, or share the calculation.
407c pt chart example

How to use the R-407C PT chart calculator

  1. Open the Refrigerant drop-down and choose R-407C. To see a sample first, use one of the example buttons above the form.
  2. Open Convert and choose Temperature → pressure or Pressure → temperature.
  3. Enter the Saturation temperature or the Gauge or absolute pressure, whichever your mode shows. Pick psig, kPag or barg for a gauge reading, psia, kPaa or bara for an absolute one.
  4. Set Chart units to °F and psig, °C and bar (gauge), or °C and kPa (gauge). This sets the units for the result and for the full chart table.
  5. If needed, open More options. Set Chart table step (Auto, 1, 2, 5 or 10 degrees) and, away from sea level, Altitude above sea level.
  6. Read the result rows. Only the rows that apply to your mode appear. For R-407C, compare Liquid pressure (bubble point) and Vapor pressure (dew point), and check the Temperature glide row.
  7. Read any warning above the result. A negative gauge value means the reading is below atmospheric pressure. A glide warning tells you which column to use for each reading.
  8. Scroll to the table under the result to see the full R-407C pressure-temperature chart at your chosen step.

Use Copy result to copy the result lines with a link. Use Copy link to save the page address, which stores every input so the same calculation reopens later. Print / save as PDF includes the inputs, results, steps, and date. Reset restores the starting example.

How do you read a PT chart?

A PT chart lists the saturation pressure of a refrigerant at each temperature. Saturation pressure is the pressure at which the refrigerant boils or condenses at that temperature. Find the temperature row, then read the pressure in the column that matches the part of the system you are measuring.

For R-407C, the chart has two pressure columns. The liquid column is the bubble point, and the vapor column is the dew point. The dew column is used for the evaporator and superheat, and the bubble column is used for the condenser and subcooling. At 40 °F, the vapor column reads 63.2 psig, which is the reference for a suction pressure in the evaporator. At 120 °F, the liquid column reads 298.6 psig, which is the reference for the condenser.

The chart temperature is the real refrigerant temperature only where liquid and vapor are both present, such as in the evaporator or condenser. In a superheated suction line or a subcooled liquid line the pressure is still about the evaporator or condenser pressure, but the pipe temperature is not the chart temperature: the difference between the two is the superheat or the subcooling.

What is the difference between bubble point and dew point?

The bubble point is the temperature or pressure at which a liquid first starts to boil and form its first vapor bubble. The dew point is the temperature or pressure at which a vapor first starts to condense and form its first drop of liquid. For a single-component refrigerant these two values are the same. For a blend such as R-407C they are different, because the blend boils and condenses across a range.

The gap between the two values is called the temperature glide. For R-407C, the glide is around 10 °F. At 70 °F, the liquid (bubble) pressure is 140.5 psig and the vapor (dew) pressure is 117.3 psig, a difference of about 23 psi. The same effect appears when pressure is fixed. At 70 psig, the liquid bubble temperature is 33.55 °F and the vapor dew temperature is 44.54 °F, a gap of about 11 °F.

Because of this glide, use the wrong column and your reading can be off by a large amount. Use the liquid column for condenser and subcooling readings, and use the vapor column for evaporator and superheat readings.

Sources

Data and methods used by this calculator (checked October 2026):

Worked examples

InputResult
R-407C, 40 °Fliquid 80.24 psig, vapor 63.16 psig
R-407C, 110 °Fliquid 260.2 psig, vapor 229 psig
R-407C, 70 psigliquid 33.55 °F, vapor 44.54 °F
R-407C, 7 °Cliquid 6.073 barg, vapor 4.833 barg

Calculated by the tool above with these values.

Frequently asked questions

What is the pressure of R-407C at 70 °F (standing pressure)?

At 70 °F, the chart gives 140.5 psig for the liquid (bubble point) and 117.3 psig for the vapor (dew point). Because R-407C is a blend, a standing pressure is not one fixed number, so both values are shown. Use the liquid value for liquid and the vapor value for vapor.

What should R-407C pressures be when running?

There is no single running pressure for R-407C. Running pressures depend on the evaporator and condenser temperatures. Convert each temperature with the calculator, then use the vapor column for suction and the liquid column for the condenser. Check the equipment manufacturer’s chart and charging instructions when they are available.

Is a PT chart in psig or psia?

This chart uses psig, which is gauge pressure relative to the atmosphere. At sea level, psia = psig + 14.696. Use the Gauge or absolute pressure input to choose the unit that matches your reading.

Why does my gauge not match the chart on the suction line?

The chart shows saturation pressure, which applies where liquid and vapor are both present. A superheated suction line contains only vapor, so the pipe temperature is above the dew-point temperature the chart gives for the gauge pressure. That difference is the superheat; measure the line temperature and use a superheat calculation for the comparison.

Does a leak change the R-407C chart values?

Yes, a leak can change the blend composition, which changes the pressure-temperature values. Manufacturers recommend charging blends as liquid. If you suspect a leak, compare your readings with the chart for the composition of the charge you have.

Does altitude change the reading?

Gauges read relative to local air pressure, and air pressure is lower at altitude. Enter your altitude under More options so the result accounts for it. At sea level, leave the field blank.