R134a pressure temperature chart (PT)
R134a saturation pressure vs temperature (PT chart): a CoolProp-generated reference table in kPa(a), bar(a), and psi(a), plus how to interpret it safely (not diagnostic targets).
An R134a pressure temperature chart (PT chart) is a saturation lookup: it relates temperature and saturation pressure for R134a when liquid and vapor coexist in equilibrium. It is useful for thermodynamic interpretation -- but it is not a universal "normal running pressure" diagnostic chart for automotive A/C systems.
What this table is (and isn't)
- It is: saturation pressure Psat(T) for R134a (two-phase equilibrium).
- It is not: "high side / low side target pressures" while a system is running.
- It is not: a substitute for OEM procedures, safety requirements, or local regulation.
If you are coming from "car A/C pressure chart" searches, start here for context: Car A/C pressure chart (static vs running) and Refrigerant PT chart (how to read it).
Pressure basis: absolute vs gauge
The table below is absolute pressure (kPa(a), bar(a), psi(a)). Many gauges display gauge pressure (relative to ambient). Converting requires local atmospheric pressure:
Pabs = Pgauge + Patm
Patm changes with altitude and weather. That is why "psig" conversions cannot be one-size-fits-all.
Learn more: Gauge vs absolute pressure (psig vs psia).
R134a saturation pressure vs temperature (reference table)
Generated using CoolProp (the same property engine used by FluidTool) at Q=0 saturation (pure fluid; bubble and dew coincide). Values are rounded for readability.
| T ( deg C) | T ( deg F) | Psat (kPa(a)) | Psat (bar(a)) | Psat (psi(a)) |
|---|---|---|---|---|
| -20 | -4 | 132.7 | 1.327 | 19.3 |
| -10 | 14 | 200.6 | 2.006 | 29.1 |
| 0 | 32 | 292.8 | 2.928 | 42.5 |
| 10 | 50 | 414.6 | 4.146 | 60.1 |
| 20 | 68 | 571.7 | 5.717 | 82.9 |
| 30 | 86 | 770.2 | 7.702 | 111.7 |
| 40 | 104 | 1016.6 | 10.166 | 147.4 |
| 50 | 122 | 1317.9 | 13.179 | 191.1 |
| 60 | 140 | 1681.8 | 16.818 | 243.9 |
| 70 | 158 | 2116.8 | 21.168 | 307.0 |
How to verify any row in FluidTool
- Open FluidTool with R134a selected: /?fluid=R134a
- Choose a Two-phase input pair (Temperature & Quality / T + Q).
- Set Q=0 and enter the temperature from the table to read Psat.
For interpretation with real line measurements, combine saturation with superheat/subcooling concepts -- and always follow OEM procedures.
Related
- R134a data sheet: basic identifiers and thermodynamic context.
- R1234yf PT chart: a parallel saturation reference table for R1234yf.
- Refrigerant PT chart: what Tsat(P)/Psat(T) means and common pitfalls.
- Back to Wiki
- Open the tool
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R134a vs R1234yf
A practical comparison of R134a and R1234yf for automotive air-conditioning, with safety, policy, and service caveats.