R404A Refrigerant44/52/4 HFC blend · Legacy low-temperature refrigeration · High-GWP installed base
R404A is a near-azeotropic A1 HFC blend that became one of the dominant refrigerants for supermarket freezers, cold rooms, ice machines, transport refrigeration and other medium/low-temperature systems after the phaseout of CFCs and HCFCs. It solved the ozone-depletion problem but introduced very high climate impact: EPA uses a 100-year GWP of 3,922, so new R404A equipment has been restricted across many U.S. and European applications while a large service base remains.
What is R404A refrigerant?
R404A contains 44% R125, 52% R143a and 4% R134a by mass. It behaves nearly azeotropically with very small glide and is classified A1. In 2026, the central issue is not whether R404A ever worked well—it did—but how to maintain or retire the installed base while moving new systems to much lower-GWP refrigerants.
R404A refrigerant properties
Use these values for research and screening. For equipment design, charging and compliance, use the exact supplier PT data, SDS, OEM documentation and regulation that governs the project.
| Property | Reference | Engineering / source note |
|---|---|---|
| Designation | R404A | ASHRAE designation |
| Nominal composition | R125/R143a/R134a = 44/52/4 mass % | Chemours thermodynamic data |
| Refrigerant type | Near-azeotropic HFC blend | Three components |
| Average molecular weight | ≈97.60 g/mol | Chemours |
| Normal boiling point | ≈ −46.45°C | Chemours |
| Critical temperature | ≈72.07°C | Chemours |
| Critical pressure | ≈37.32 bar | Chemours |
| ODP | 0 | No ozone depletion |
| 100-year GWP | 3,922 | EPA Technology Transitions |
| Safety classification | A1 | Lower toxicity / no flame propagation |
EPA Technology Transitions uses the values shown on this page. Older product literature may use IPCC AR4/AR5 or another assessment, so a different number is not automatically an error.
Where is R404A used?
Applications must be evaluated by system type, charge, compressor, heat exchanger, safety class and current regulation. The examples below describe recognized use contexts, not automatic approval for every installation.
Supermarket low-temperature racks
A historic flagship application, especially freezer circuits.
Walk-in freezers & cold rooms
Large installed base in food service and distribution.
Remote condensing units
Common legacy use, although SNAP restrictions ended R404A new/retrofit use in this category years ago.
Refrigerated food processing
Legacy equipment may still contain R404A; new-equipment SNAP restrictions started in 2021.
Transport refrigeration
Historically used in road/marine/reefer equipment; newer product restrictions have moved the market toward alternatives.
Ice machines & specialty low-temperature systems
R404A remains present in installed equipment even as new product rules prohibit it in many categories.
Continue through the Refrigerant Replacements and Low-GWP Refrigerants hubs for broader selection context.
Why R404A became so popular—and why its GWP became a problem
R404A provided an A1, zero-ODP replacement path for R502 and other older low-temperature refrigerants. Its near-azeotropic behavior, compressor availability and broad component ecosystem made it easy to standardize.
The tradeoff is climate impact. R143a, which makes up 52% of R404A, has very high GWP and drives much of the blend’s overall GWP of 3,922.
Once HFC policy shifted from ozone protection to climate impact, R404A became an early target for substitution.
R404A is near-azeotropic, but it is still a blend
Chemours publishes separate bubble and dew properties for R404A, but the difference is small compared with R407C, R448A, R454C or R455A.
Small glide simplifies field service and heat-exchanger behavior, which was one reason R404A was popular.
Even so, refrigerant should still be handled according to blend charging/recovery guidance, and contaminated recovery cylinders should not be assumed to contain specification-grade R404A.
Can existing R404A systems still be repaired in the U.S.?
Yes. EPA’s current HFC FAQ explains that stores can maintain and repair legacy R404A supermarket systems throughout the useful life of the equipment.
Technology Transitions restrictions focus heavily on new products and installation of new systems. Components can continue to be used for maintenance of existing systems under the rule’s definitions.
That distinction matters for capital planning: an owner can maintain a legacy rack while separately planning retrofit or replacement.
Choosing between R448A, R449A and sub-150 new-system refrigerants
R448A and R449A preserve an A1 safety class and substantially reduce GWP versus R404A, making them useful transition/retrofit options for compatible systems.
However, their GWPs around 1,400 are still above the 150/300 thresholds that appear in long-term U.S. retail-food rules.
For a new system expected to operate well into the 2030s, A2L sub-150 blends such as R454C/R455A, hydrocarbons, CO₂ or other architecture-specific options may provide stronger regulatory longevity.
R404A vs R448A
The table highlights engineering differences rather than implying direct interchangeability.
| Characteristic | R404A | R448A |
|---|---|---|
| Type | Near-azeotropic HFC blend | Zeotropic HFC/HFO blend |
| EPA GWP | 3,922 | 1,386 |
| Safety class | A1 | A1 |
| Temperature glide | Very small | Meaningful |
| Typical role | Legacy low-temp installed base | R404A/R507A transition retrofit |
| New U.S. retail-food role | Restricted in many categories | Interim only in selected categories |
| Long-term direction | Managed service / retirement | Bridge toward lower-GWP systems |
R404A safety: A1, but high GWP makes leak prevention especially important
R404A is A1 and therefore not primarily constrained by flammability. Large releases can still displace oxygen, liquid refrigerant can cause frostbite and hot work can create hazardous decomposition products. Because each kilogram leaked has high climate impact, leak prevention and recovery have unusually high environmental value.
Leak prevention
R404A’s high GWP makes chronic supermarket leakage particularly consequential.
Recovery / reclamation
Recover refrigerant during service and equipment retirement.
Confined spaces
Large charge systems still require ventilation and concentration risk assessment.
Actual risk depends on charge, release rate, pressure, room volume, ventilation, ignition sources, equipment construction, alarm logic and service condition.
See the Refrigerant Safety Guide for classification context.
R404A refrigerant leak detection
Validate detector response to the finished blend
Use R404A-compatible fixed or portable refrigerant detection. GasNose lists R404A as an A1 high-GWP refrigerant and recommends refrigerant-calibrated infrared area monitoring or compatible service leak detection. Large supermarket/cold-storage systems benefit from continuous monitoring because even small annual leak percentages can represent substantial mass and climate impact.
Portable service leak detectors, fixed area monitors, A2L mitigation sensors and refrigerant identifiers perform different functions. Define the alarm action and concentration range before selecting the technology.
Regulatory position of R404A in 2026
United States
EPA SNAP made R404A unacceptable in new supermarket systems from 2017, new remote condensing units from 2018 and new refrigerated food processing/dispensing equipment from 2021, with additional category-specific dates. Current Technology Transitions rules also prohibit R404A in multiple new refrigerated-transport and ice-machine product categories. EPA nevertheless states that legacy R404A systems can continue to be maintained and repaired throughout their useful life.
European Union
R404A is strongly affected by EU F-gas policy because of its very high GWP. Regulation (EU) 2024/573 continues the transition away from high-GWP fluorinated gases and adds a 2032 servicing prohibition for stationary refrigeration using Annex I F-gases with GWP 750 or more, subject to listed reclaimed/recycled exceptions and other exclusions.
Is R404A being phased out?
R404A is a legacy-service refrigerant, not a future new-system platform. Existing equipment can remain economically important, but every major repair should be evaluated against retrofit or replacement options because regulatory and supply pressure will continue to increase.
U.S. refrigeration limits differ by cold storage, supermarket, remote condensing, stand-alone product, industrial process and chiller category. A refrigerant may fit one pathway and fail another.
Use the Refrigerant Regulations Hub for regional research.
What should be compared with R404A?
Compare the real equipment pathway: retrofit vs new system, A1 vs A2L capability, GWP threshold, glide, compressor envelope, energy efficiency and service ecosystem.
Practical misconceptions about R404A
“R404A is completely illegal in existing U.S. systems.”
EPA allows legacy systems to be maintained and repaired; restrictions vary by new/retrofit category.
“R404A and R507A are the same blend.”
They have similar applications but different compositions and GWP.
“R448A is automatically a drop-in.”
Retrofit needs compressor, valve, glide and discharge-temperature review.
“A1 means leaks are only a cost issue.”
R404A’s very high GWP makes leakage a major climate and regulatory concern.
R404A refrigerant FAQ
Concise answers to common composition, retrofit, glide, safety and regulation questions.
What is R404A?
What is the composition of R404A?
What is the EPA GWP of R404A?
Is R404A flammable?
Does R404A have glide?
Can existing R404A supermarket systems still be repaired in the U.S.?
Can R404A be used in new U.S. supermarket systems?
What are common R404A retrofit options?
What are lower-GWP new-system options?
How should R404A leaks be monitored?
R404A sources and further reading
This profile uses current EPA regulatory references plus refrigerant supplier, NIST, scientific and GasNose resources. Re-check the latest edition before design or compliance decisions.
Working with R404A or planning a refrigerant transition?
Compare GWP, safety class, temperature glide, equipment compatibility and regulatory lifetime before selecting a refrigerant.
Technical Notice: This page is for refrigerant research and general technical reference. Refrigerant suitability, permitted charge, equipment approval, leak mitigation, servicing procedures and regulatory compliance depend on the exact equipment, installation and jurisdiction. Always verify current manufacturer documentation, SDS, applicable standards and local regulations before selecting, replacing, charging or servicing a refrigerant.