R-404A Pressure at 135°F — Saturation P-T Data
How This Was Calculated
Saturation pressure interpolated from ASHRAE tabular data for R404A. Elevated pressure — high-side normal range.
- P_sat
- Saturation pressure: 427 PSI
- T_input
- Input temperature: 135°F
- T_data
- ASHRAE tabular reference data: R404A
Important Considerations
At 135°F, R404A is at 427 PSI — in the elevated range above 300 PSI. This is within normal high-side operating conditions for hot weather but warrants attention. Confirm condenser coil is clean, fans are operating, and ambient temperature is within equipment rated limits. Monitor for pressure trending higher over a season, which may indicate refrigerant overcharge or coil fouling.
R-404A has a very high GWP (3,922) and is a priority phase-down target under the AIM Act. EPA regulations restrict its use in new refrigeration equipment. Replacements include R-448A, R-449A, and R-744 (CO2) transcritical systems for commercial refrigeration.
135°F is an extreme operating temperature — above the rated ambient limit for most residential HVAC equipment (typically 115–120°F). At this condition, R404A reaches very high saturation pressure which stresses compressor windings and discharge valves. Most manufacturers void warranty for operation above rated ambient. Consider condenser shading, pre-cooling, or equipment with expanded ambient ratings for installations in direct sun in hot climates.
The saturation pressure shown (for R404A at 135°F) is the baseline for measuring superheat and subcooling. Suction superheat = suction line temperature minus evaporator saturation temperature. Subcooling = condensing saturation temperature minus liquid line temperature. Typical targets: 8–12°F superheat at the evaporator (TXV systems), 10–20°F subcooling at the condenser. Deviations indicate improper charge, metering device issues, or non-condensables.
R404A — consult ASHRAE Standard 34 and manufacturer safety data sheet for handling requirements. EPA Section 608 certification is required for purchase and handling.
R404A has a GWP of 3,922 — meaning 1 lb released equals 3,922 lbs of CO2 equivalent warming over 100 years. This places it in the high-GWP category subject to accelerated phase-down under the AIM Act (American Innovation and Manufacturing Act). EPA regulations are reducing HFC production and import allowances through 2036. Lower-GWP alternatives are available: R-32 (GWP 675), R-454B (GWP 466), and R-290 (GWP 3) depending on application.
Saturation pressure-temperature data for R404A derived from ASHRAE Fundamentals Handbook, Chapter 30 (Thermophysical Properties of Refrigerants), and verified against manufacturer published data (Chemours Opteon, Honeywell Solstice). Values represent saturated conditions at sea level.