R-404A PT Chart and Refrigerant Profile

Where you will find R-404A

R-404A is the refrigerant in most US low- and medium-temperature commercial equipment built before the 2025–2027 Technology Transitions dates: reach-in and walk-in coolers and freezers, display and storage cases, ice machines and truck or trailer refrigeration units (Arkema). It took over from R-502 in low-temperature work and from R-22 in many low- and medium-temperature systems.

Confirm the refrigerant on the condensing-unit or compressor nameplate and on any retrofit tag before you connect. R-404A and R-507A run close enough that a mislabeled system is easy to miss: at 40°F dew, R-404A reads 85.4 psig and R-507A 89.2 psig on this site’s computed charts. Where a system has been retrofitted to R-448A or R-449A, there should be a tag; the pressure-temperature behavior of those blends is very different because of their glide.

Charging R-404A

R-404A is a near-azeotropic 400-series blend. Charge it as liquid from the cylinder, which is the standard rule for 400-series blends, so the composition in the system matches the cylinder. Its glide is small (under 1.3°F across the chart), but the bubble and dew columns still differ: at 40°F the table gives 86.9 psig bubble and 85.4 psig dew.

Read the dew column against suction pressure for superheat and the bubble column against liquid-line pressure for subcooling. On a TXV or EEV system, charge to the equipment manufacturer’s subcooling or charging instructions and check the result with the subcooling calculator. Capillary-tube self-contained units are charged by weight to the nameplate.

The target superheat method is built on CEC Title 24 Reference Appendices Table RA3.2-2, whose valid range (55–115°F outdoor dry bulb, return air at least 70°F dry bulb) is written for comfort air conditioners. It does not fit a freezer or a medium-temperature case.

There is no single “normal” R-404A suction pressure. Suction pressure follows the saturated evaporating temperature the system was designed for: at -20°F dew the chart gives 16.0 psig, at 20°F dew 55.3 psig. Get the design evaporating temperature from the case or unit manufacturer, then read the dew column. Fixed pressure ranges copied from blogs, without box temperature or ambient, are a common source of misdiagnosis.

Oil and compatibility

R-404A uses POE (polyolester) oil. Chemours notes that equipment makers recommend POE when an R-502 system is converted to R-404A, and Copeland’s approved-lubricant bulletin (AE 93-11) lists POE for R-404A compressors. Use the oil grade on the compressor label.

When an R-404A system is retrofitted to R-448A or R-449A, Solstice and Chemours both state that the existing POE is suitable, so no oil change is normally needed for that move. The refrigerant oil guide covers POE, mineral oil and alkylbenzene mixing in more detail.

Safety, handling and recovery

R-404A is ASHRAE safety class A1: lower toxicity and no flame propagation in the standard test.

Under Section 608 an R-404A system is a high-pressure appliance (liquid saturation pressure between 170 and 355 psia at 104°F, 40 CFR 82.152), so you need Type II or Universal certification, and sale is restricted to certified technicians (82.154(c)). Required recovery levels for equipment made after November 15, 1993 (40 CFR 82.156, Table 1): 0 in Hg for a charge under 200 lb, 10 in Hg at 200 lb or more. A recovery machine certified to Appendix B3 (AHRI 740) is the right class for this non-flammable refrigerant; see recovery machine compatibility.

Since January 1, 2026, appliances holding 15 lb or more of HFC are covered by the leak repair rules in 40 CFR 84.106, and commercial refrigeration systems of 1,500 lb or more need automatic leak detection (84.108).

Older R-404A cylinders are orange. Under AHRI Guideline N-2017, all new refrigerant containers since January 1, 2020 are light green-gray (RAL 7044), and the legacy color appears only on the label, so read the label. Recovery cylinders are gray with a yellow top (AHRI Guideline K). More in the cylinder color guide.

Status and replacements

Servicing existing R-404A equipment is legal. Supply is shrinking under the AIM Act allowance cuts in 40 CFR 84.7: 60% of baseline in 2024–2028, 30% in 2029–2033, 20% in 2034–2035 and 15% from 2036.

For new equipment, R-404A’s GWP of 3,922 is above every limit in its sectors under 40 CFR 84.54. New stand-alone retail units have been capped at 150 GWP since January 1, 2025, and R-404A is named as restricted in new road and marine transport units from that date. The May 2026 final rule (91 FR 31284) set a 1,400 GWP limit for new remote condensing units from July 27, 2026 and new supermarket systems from January 1, 2027, and a 700 limit for new cold storage from July 27, 2026. The lower 150/300 limits for those sectors apply from January 1, 2032. EPA SNAP had already listed R-404A as unacceptable in new cold storage warehouses from January 1, 2023.

From January 1, 2029, servicing of supermarket systems, refrigerated transport and automatic commercial ice makers must use reclaimed refrigerant (40 CFR 84.112(e)). Other R-404A equipment is not covered by that requirement.

Retrofit options for existing systems include R-448A and R-449A (both A1, POE, GWP just under 1,400), R-452A in transport, and R-407A or R-407F. New equipment is moving to A2L blends such as R-454A, R-454C and R-455A, to CO2 (R-744), and to propane (R-290) in self-contained units. Compare the options in R-404A replacement and R-404A vs R-507A.

Common questions

Is there a direct drop-in replacement for R-404A?

No replacement is a pure top-off. R-448A and R-449A are the usual retrofit blends; their makers say the existing POE can stay, and Chemours suggests starting an R-449A retrofit at about 85% of the original charge. Follow the refrigerant maker’s retrofit guideline and the compressor maker’s approval.

What oil does R-404A use?

POE (polyolester), in the grade the compressor maker lists; Copeland’s bulletin AE 93-11 lists POE for R-404A. When R-502 systems were converted to R-404A, equipment makers recommended changing to POE (Chemours).