R-438A
Quinary HFC blend with two small hydrocarbon components (R-32/R-125/R-134a/R-600/R-601a 8.5/45/44.2/1.7/0.6 mass) — A1 safety, GWP 2265. R-22 retrofit refrigerant designed for mineral oil compatibility.
Lower toxicity (Occupational Exposure Limit ≥ 400 ppm). No flame propagation in air at standard atmospheric pressure and 60°C. R-134a, R-22, R-410A, R-404A, R-744 (CO2) are A1.
- Flammability
- None (no flame propagation)
- Toxicity
- Lower (OEL ≥ 400 ppm)
Classification per ANSI/ASHRAE Standard 34-2022. See full reference.
Saturation pressure-temperature curve
No PT chart in this build — see manufacturer datasheet. R-438Ahas a published PT chart in its manufacturer's technical datasheet (linked below). The chart has not been transcribed into this site's dataset. For service work, use the manufacturer's published PT chart directly — link below.
- manufacturer-datasheetHoneywell International Inc., Genetron Performax LT (R-438A) Technical Information / Material Data Sheet.Published PT chart and physical property data for R-438A retrofit refrigerant.https://www.honeywell-refrigerants.com/americas/
- standardsAHRI Standard 700-2019 Specifications for Refrigerants — R-438A specification entry.https://www.ahrinet.org/search-standards
At a glance
Chemistry
Lubricant compatibility
Hydrocarbon components aid miscibility with mineral oil. Marketed by Honeywell as a 'no oil change' R-22 retrofit.
Blend composition
- R-328.5%
- R-12545.0%
- R-134a44.2%
- R-6001.7%
- R-601a0.6%
Trade names
- Genetron MO99Honeywell
Common applications
- R-22 retrofit (commercial AC, refrigeration)
- Compatible with mineral oil systems
Properties
- Boiling point (1 atm)-43.0°C / -45.4°F
- Critical point184.1°F at 584 PSIG
- Molar mass99.10 g/mol
- Temperature glide12.6°F
- ODP0
- GWP (AR5, 100-yr)2265
- GWP (AR6, 100-yr)2440
What is R-438A?
R-438A is a quinary HFC blend with two small hydrocarbon components: R-32 (8.5%) + R-125 (45%) + R-134a (44.2%) + R-600 (1.7%) + R-601a (0.6%) by mass [ashrae34]. The hydrocarbon components (R-600 n-butane and R-601a isopentane, totaling 2.3% by mass) serve the same role as R-422D's R-600a — bridging the polarity gap between HFC components and mineral oil to enable R-22 retrofit without oil change.
Honeywell markets R-438A as Genetron Performax LT. It is one of several Honeywell-branded R-22 retrofit alternatives alongside R-422D (Genetron MO99); both target the mineral-oil-compatible R-22 retrofit market with slightly different compositions optimized for different equipment categories.
Where R-438A is used
- R-22 retrofit in residential and light commercial AC
- Commercial refrigeration retrofit
- Heat pump retrofit from R-22
- Honeywell-aligned retrofit market segment
Regulatory & phase-down status
R-438A faces EPA AIM Act phase-down pressure due to its high GWP (2265) [aimact]. The blend is acceptable for R-22 retrofit but not specified for new equipment installations.
For service of existing R-438A retrofits, supply will continue indefinitely. New R-22 retrofit decisions in 2026 increasingly favor full equipment replacement (R-32 or R-454B) rather than refrigerant-only retrofit to R-438A or similar HFC blends.
Service notes
Mineral oil, alkylbenzene, or POE all compatible [ahri700]. R-438A can be charged into R-22 equipment without oil change. The 10°F glide affects service measurement — use dew curve for superheat, bubble curve for subcooling. A1 classification means no A2L procedures required.
Phase-down timeline
No phase-down milestones documented for R-438A in this build. This may mean: (a) no regulatory phase-down currently published; (b) the refrigerant has local regulatory schedules not yet transcribed into the site dataset; or (c) it is a specialty refrigerant outside the main regulatory frameworks. For authoritative current status, consult the EPA AIM Act allocations (40 CFR Part 84), EU F-Gas Regulation 517/2014 + 2024/573, and the relevant national implementations of the Kigali Amendment.
Global warming potential, in context
R-22 retrofit blends
Retrofit and replacement paths
R-438A replaces
Replacements for R-438A
Reading the R-438A PT chart
R-438A is zeotropic with ~10°F glide — PT chart shows bubble and dew curves. Use dew curve at suction pressure for superheat; bubble curve at discharge for subcooling.
At 70°F R-438A bubble is approximately 130 PSIG / dew approximately 115 PSIG (CoolProp 7.2.0). Pressure envelope close to R-22 — standard 500 PSI manifold gauges adequate.
Quinary blend — five components for optimized retrofit performance
R-438A's five-component composition is unusual — most HFC blends use 2-4 components. The five-component design (R-32 + R-125 + R-134a + R-600 + R-601a) was engineered to balance multiple requirements: A1 safety class, mineral oil compatibility, R-22 pressure-envelope match, capacity preservation, GWP minimization within those constraints.
The R-32 component (8.5%) provides some volumetric capacity. R-125 (45%) is the flammability suppressor. R-134a (44.2%) provides moderate-temperature capacity. R-600 (n-butane, 1.7%) and R-601a (isopentane, 0.6%) bridge the polarity gap for mineral oil miscibility.
GWP 2265 — lower than R-422D but still high
R-438A's GWP of 2265 is between R-22 (1810) and R-422D (2729). The lower R-125 content (45% vs R-422D's 65.1%) reduces the GWP burden compared to R-422D.
Both R-438A and R-422D face AIM Act phase-down pressure for new equipment specification. Modern low-GWP R-22 retrofit doesn't have a great solution — the mineral-oil-compatibility requirement essentially forces use of high-GWP HFC blends. The alternative is POE oil change (enabling R-407C use, GWP 1774) or full equipment replacement.
How to think about R-438A in 2026 and beyond
R-438A occupies the same narrowing niche as R-422D — service of existing R-22 retrofit installations. New R-22 retrofit decisions in 2026 increasingly favor full equipment replacement to R-32 or R-454B rather than refrigerant-only retrofit.
For service technicians, R-438A work is occasional — Honeywell-specified retrofits from the 2010s era. Service supply will continue indefinitely; pricing trends parallel other high-GWP HFC blends through the AIM Act schedule.
Frequently asked
›What is R-438A used for?
R-22 retrofit refrigerant for systems where oil change is undesirable. Honeywell markets R-438A as Genetron Performax LT, positioned alongside R-422D (Genetron MO99) for mineral-oil-compatible R-22 retrofit applications [honeywellgenetron].
The five-component composition is engineered for slightly different operating characteristics than R-422D — R-438A has lower R-125 content (45% vs R-422D's 65.1%) and includes R-32 (8.5%) for capacity contribution.
›What's R-438A's GWP?
2265 per IPCC AR5 — higher than R-22 (1810) but lower than R-422D (2729) [ipccar5]. R-438A faces AIM Act phase-down pressure for new equipment but remains acceptable for R-22 retrofit service.
›What's the difference between R-438A and R-422D?
Both are Honeywell HFC retrofit blends for R-22 with mineral oil compatibility. R-438A is quinary (5 components, including R-32 for capacity); R-422D is ternary (3 components, no R-32). R-438A has lower GWP (2265 vs 2729) and includes the R-32 component; R-422D's simpler composition is older (mid-2000s).
Performance is broadly similar — both target the same R-22 retrofit market with mineral-oil compatibility. The choice between them is typically driven by equipment OEM specification or distributor availability.
›Can I retrofit R-22 to R-438A without oil change?
Yes — the R-600 n-butane and R-601a isopentane hydrocarbon components (2.3% combined) enable mineral oil miscibility, allowing mineral oil retention through retrofit. Standard procedure: recover R-22, replace filter-drier, evacuate to 500 microns, recharge R-438A by weight to OEM nameplate.
›Why does R-438A contain hydrocarbons?
Mineral oil miscibility. HFC refrigerants (R-32, R-125, R-134a) are not miscible with mineral oil — without hydrocarbon addition, R-438A would have oil-return problems in R-22 equipment retaining mineral oil. The 2.3% combined R-600 + R-601a hydrocarbon content bridges the polarity gap, enabling acceptable oil-return behavior.
The hydrocarbon content is too small to change the A1 safety classification — the non-flammable HFC majority dominates.
›Is R-438A safe to handle?
ASHRAE class A1 — non-toxic and non-flammable [ashrae34]. Standard HFC service procedures apply.
›Should I use R-438A or R-422D for R-22 retrofit?
Both serve the same retrofit market. R-438A has lower GWP (2265 vs R-422D's 2729) and includes R-32 for slightly different performance characteristics. The choice is typically driven by Honeywell distributor recommendations and equipment OEM specifications.
In 2026, the better answer is often neither — full equipment replacement to R-32 or R-454B (sub-700 GWP) typically wins the retrofit-vs-replace economic comparison for older R-22 equipment.
Sources & citations
- [1]ASHRAE Standard 34-2022
- [2]IPCC AR5 (2014) Working Group I, Chapter 8, Table 8.A.1
- [3]EPA AIM Act — 40 CFR Part 84 Subpart BFinal Rule Oct 2021https://www.epa.gov/climate-hfcs-reduction
- [4]EPA SNAP — R-438A acceptable for R-22 retrofit
- [5]CoolProp 7.2.0
- [6]AHRI Standard 700-2019
- [7]Honeywell Genetron Performax LT (R-438A) Technical Information