Free Tools
Every refrigerant, one page.
From ether and ammonia to Freon™, R-410A, and the new A2Ls — a working reference for HVAC and appliance pros. Search the specs that matter on a job (GWP, ODP, safety class, glide, oil, retrofit paths), walk the history, and get the rules straight: Montreal, Section 608, the R-22 sunset, and the AIM Act phasedown.
First, the word "Freon"
Freon is a brand name, not a substance — a trademark registered in 1930 by Kinetic Chemicals (a DuPont–General Motors venture, the mark now held by Chemours) that has covered many different refrigerants over the decades: Freon 12 was R-12, Freon 22 is R-22, and today's Freon™ MO99 is R-438A. Like Kleenex, the name went generic — when a homeowner says "my AC needs Freon," they usually mean whatever refrigerant the system takes.
The unambiguous way to talk about refrigerants is the ASHRAE R-number (R-22, R-410A, R-744…), assigned under ASHRAE Standard 34 along with a safety class: a letter for toxicity (A lower, B higher) and a number for flammability (1 none, 2L mildly flammable, 2 flammable, 3 highly flammable). Two more numbers run the industry: ODP (ozone depletion potential, R-11 = 1.0) and GWP (global warming potential, CO₂ = 1). Blends add glide — a zeotropic mixture boils across a temperature range instead of at one point, which changes how you charge and diagnose.
A century and a half, five eras.
Refrigerant history runs in a loop: the dangerous naturals were replaced by "perfectly safe" chemistry, the chemistry turned out to bite back twice — first the ozone layer, then the climate — and the industry is now circling back toward low-impact molecules, with better engineering carrying the safety load.
Vapor compression is born
Jacob Perkins patents the first vapor-compression machine, running on ethyl ether. The cycle a modern tech gauges every day — compress, condense, expand, evaporate — is already all there.
Ammonia industrializes cold
Carl von Linde's ammonia compression plants put refrigeration in breweries and packing houses. Ammonia (R-717) is brilliant thermodynamically and never really leaves industrial work — but it's toxic, and it wants steel, not copper.
Home fridges arrive — and leak
Early household refrigerators run on sulfur dioxide (R-764) and methyl chloride (R-40). Leaks in kitchens injure and kill; a string of methyl-chloride deaths in the late 1920s makes national news and creates the demand for something safe enough to sleep next to.
Midgley's miracle: R-12 and the Freon trademark
Thomas Midgley Jr. and Albert Henne at GM's Frigidaire lab synthesize dichlorodifluoromethane — R-12 — nonflammable, low-toxicity, and a superb refrigerant. Midgley famously inhales it and blows out a candle at the American Chemical Society. Kinetic Chemicals brands the family "Freon," and the safety problem looks solved.
Chlorinated chemistry conquers everything
R-11 fills low-pressure centrifugal chillers, R-12 takes fridges and car AC, R-22 (an HCFC, commercialized in the 1950s) becomes the air-conditioning refrigerant, and the azeotrope R-502 (1961) owns supermarket low-temp racks. Cheap comfort cooling reshapes American homes, work, and the Sun Belt.
Molina & Rowland connect CFCs to the ozone layer
Their Nature paper shows CFCs drift to the stratosphere, where UV light frees chlorine that catalytically destroys ozone. Industry pushback is fierce — until British Antarctic Survey measurements confirm a gaping seasonal ozone hole in 1985. The work earns the 1995 Nobel Prize in Chemistry.
The Montreal Protocol
Nations agree to phase out ozone-depleting substances on a schedule — eventually ratified by every UN member, and arguably the most successful environmental treaty ever. CFC production in developed countries ends after 1995; HCFCs get a longer fuse.
The Clean Air Act makes it personal
US Clean Air Act amendments create Section 608 (stationary) and Section 609 (auto AC): venting becomes illegal in 1992–95, technician certification becomes mandatory, and recovery machines become as standard as gauges. Meanwhile new cars switch from R-12 to R-134a.
Chlorine-free replacements take over
HFCs carry no chlorine, so zero ODP: R-134a in cars, fridges, and chillers; R-404A and R-507A replace R-502 in supermarkets; R-407C bridges R-22 equipment; and in 1996 Carrier launches R-410A as Puron® — higher pressure, POE oil, and the future of residential AC.
R-22's long goodbye begins
No new R-22 equipment may be made or imported into the US. A decade of "dry-ship" condensers, retrofit blends (R-407C, R-438A/MO99), and climbing R-22 prices follows. Total US production and import end January 1, 2020; servicing continues on reclaimed gas only.
Cars jump first — to an HFO
R-134a's GWP (~1,430) makes it the next target. Driven by EU rules, automakers adopt R-1234yf — an HFO with GWP under 1 — which becomes standard across new US vehicles through the late 2010s. Separate couplers, machines, and a mild-flammability rating come with it.
Kigali and the AIM Act target HFCs
The Kigali Amendment extends Montreal to HFCs worldwide (US ratified 2022). Domestically, the AIM Act (2020) orders an 85% phasedown of HFC production and import by 2036, allowance by allowance — the engine behind every current refrigerant transition.
The A2L changeover in comfort cooling
New residential and light-commercial AC and heat pumps must use refrigerants under GWP 700 — in practice R-454B and R-32. Mildly flammable A2Ls bring leak sensors, UL 60335-2-40 listings, red-banded cylinders, and a tooling refresh. Meanwhile CO₂ racks spread in supermarkets and propane/isobutane own self-contained boxes.
Where the curve is pointed
The AIM phasedown bottoms out at 15% of baseline HFC production. Expect the rest of a working career to be spent on A2L blends, CO₂, hydrocarbons, and ammonia — plus decades of legacy R-410A and R-22 equipment that still needs honest service.
Browse every type.
36 refrigerants across five families — searchable by number, name, trade name ("Freon", "Puron", "MO99"…), or what's in the blend. Open a card for the story, the field notes, and the rules attached to it.
36 shown
Side by side.
Pick up to three and line up the numbers — handy for the "what do we replace it with" conversation. Defaults to the changeover every residential tech is living through right now.
The rulebook.
The short, accurate version of the law — US federal rules as they stand in mid-2026. Summaries, not legal advice; the regs themselves (40 CFR Part 82 and Part 84) control.
GlobalMontreal Protocol & the Kigali Amendment
Signed in 1987 and ratified by every UN member state, the Montreal Protocol phases out ozone-depleting substances by class: CFC production in developed countries ended after 1995; HCFCs followed a step-down ending (for nearly all purposes) in 2020, with a servicing tail to 2030. The stratospheric ozone layer is now on track to recover around mid-century — the treaty worked.
The Kigali Amendment (2016) bolted HFCs onto the same machinery — not for ozone (HFCs carry no chlorine) but for climate. The US ratified it in 2022, and the AIM Act is how it's implemented domestically.
EPASection 608 — the technician's law
Venting is illegal. Knowingly releasing refrigerant from stationary equipment has been prohibited since 1992 for CFCs/HCFCs and since 1995 for substitutes like HFCs (a short exempt list exists — e.g., CO₂, and hydrocarbons in specific listed appliance types). De minimis releases during good-faith recovery are not violations. Fines can run into tens of thousands of dollars per day, and EPA has paid bounties to whistleblowers.
Certification is mandatory for anyone who opens the refrigerant circuit, in four flavors:
- Type I — small appliances (under 5 lb charge, factory-sealed): fridges, window units, dehumidifiers.
- Type II — high-pressure equipment: split AC, heat pumps, supermarket racks. Most HVAC techs.
- Type III — low-pressure equipment: centrifugal chillers on R-11, R-123, R-1233zd.
- Universal — all three. Certification doesn't expire.
Sales restriction: ozone-depleting refrigerants and (since 2018) most HFCs may only be sold to certified techs or their employers. Recovery to prescribed vacuum levels is required before opening a system; refrigerant can be recycled for same-owner reuse, but resale requires reclamation to AHRI-700 purity by an EPA-certified reclaimer.
Leak repair: for appliances over 50 lb of ozone-depleting refrigerant, annualized leak rates above 10% (comfort cooling), 20% (commercial refrigeration), or 30% (industrial process) trigger mandatory repair timelines and records. The 2024 AIM-Act refrigerant-management rule extends similar duties to HFC systems — generally those holding 15 lb or more of refrigerant with GWP over 53, with automatic leak detection required on the biggest (1,500 lb+) systems, phasing in from 2026.
EPASection 609 — automotive AC
Motor-vehicle AC has its own certification (Section 609), its own approved recovery/recharge equipment standards (SAE J2843 and friends for R-1234yf), and its own famous exception: small cans under 2 lb of automotive refrigerant with self-sealing valves may be sold to non-certified consumers for DIY top-ups. That exception is why the parts store shelf exists; it does not extend to stationary equipment or to bulk cylinders.
DatesThe R-22 sunset, in three dates
| Jan 1, 2010 | No new R-22 equipment manufactured or imported; production allowed only for servicing existing systems. |
|---|---|
| Jan 1, 2020 | All US production and import of R-22 ends. |
| Today | Service runs entirely on recovered, recycled, and reclaimed R-22 (plus retrofit blends like R-407C and R-438A). Running an R-22 system is perfectly legal — feeding a leaky one is just expensive. |
The same 2020 cutoff hit R-142b; other HCFCs (like R-123 for chillers) kept a servicing-production allowance that ends January 1, 2030.
AIM ActThe HFC phasedown & the 2025 equipment transition
The AIM Act (December 2020) directs EPA to cut HFC production and import to 15% of baseline by 2036, using tradeable allowances weighted by GWP:
| 2022–23 | 90% of baseline (−10%) |
|---|---|
| 2024–28 | 60% of baseline (−40%) |
| 2029–33 | 30% of baseline (−70%) |
| 2034–35 | 20% of baseline (−80%) |
| 2036 on | 15% of baseline (−85%) |
The companion Technology Transitions rule (2023) sets sector GWP caps on new equipment: residential and light-commercial AC and heat pumps are capped at GWP 700 from January 1, 2025 (hence R-454B and R-32), with a limited window to install previously-built R-410A systems; many new refrigeration categories are capped at GWP 150–300 over 2025–2028. None of it requires retiring existing equipment — the squeeze is on supply and price of high-GWP gas, exactly like the R-22 playbook. Several states (California's CARB rules most prominently) layer their own requirements on top.
SafetyThe A2L rulebook — what actually changes
A2L means mildly flammable: hard to ignite, low flame speed, and a fraction of propane's energy — but not nothing. The practical changes:
- Listed equipment: systems are built and certified to UL 60335-2-40, with charge limits tied to room size and, where required, built-in refrigerant detection that drives the blower to dilute a leak (ASHRAE 15 / 15.2 and the 2024 model codes carry this into installation practice).
- Tools: A2L-rated recovery machines, vacuum pumps, and leak detectors; recovery cylinders rated for flammables. Cylinders wear a red band on the shoulder (and since AHRI's 2020s guideline change, all refrigerant cylinders are otherwise the same gray-green — read the label, not the paint).
- Practice: nitrogen purge before brazing (which was always the standard), no open flame into a charged circuit, ventilate the work area, and mind transport quantities in enclosed vehicles.
- Same 608 rules: venting prohibitions, certification, and recovery apply to A2Ls like anything else.
HardwareCylinders, recovery tanks & DOT basics
- Disposable (DOT-39) cylinders are single-trip. Refilling one is a federal offense and a shrapnel hazard — recover what's left, then render it useless per the markings.
- Recovery cylinders (gray body, yellow shoulder) are refillable but live under DOT rules: hydrostatic retest every five years (stamped on the collar), and never filled past 80% by weight — liquid expands, hydraulic rupture doesn't negotiate.
- Color is no longer chemistry. Legacy paint (green R-22, rose R-410A, light blue R-134a, orange R-404A…) was retired by AHRI Guideline N — new cylinders are a uniform gray-green, flammables get the red band, and the only trustworthy identifier is the printed label and, when in doubt, pressure-temperature check against the SDS.
Asked on every job site.
Straight answers to the questions homeowners and apprentices actually ask.
Is Freon illegal now?
Freon is a trademark that has covered many refrigerants, so the honest answer is "which one?" R-12 production ended in the mid-1990s; R-22 production and import ended January 1, 2020. Owning and running equipment on either is completely legal — servicing continues on recovered and reclaimed supply, which is why topping up an R-22 leak costs what it costs.
Can I buy refrigerant without certification?
Mostly no — Section 608 restricts sales of ODS refrigerants and most HFCs to certified technicians. The one consumer-facing exception: small cans (under 2 lb) of automotive refrigerant with self-sealing valves for DIY car AC. If a marketplace listing offers a 25-lb jug of R-410A to anyone with a credit card, somebody in that transaction is breaking the rules.
Do I have to replace my R-410A system now that it's being phased down?
No. The 2025 GWP-700 cap applies to newly manufactured equipment, not yours. R-410A will be produced (in shrinking allowance-controlled volumes) and reclaimed for service for many years. The realistic effect is gradually rising refrigerant prices over the system's remaining life — the same arc R-22 owners lived through.
Are the new A2L refrigerants dangerous?
They're mildly flammable — class 2L means low burning velocity and a narrow window of ignitable conditions; a leak into a room is very hard to light off, and equipment is listed with sensors and mitigation where charge sizes demand it. Treat them with A2L-rated tools and the training, and they're a manageable evolution, not a hazard leap. (Perspective: your customer's grill tank is A3.)
Recovery, recycling, reclamation — what's the difference?
Recovery = getting refrigerant out of the system into a cylinder, period. Recycling = cleaning it up (oil separation, moisture/acid filtration) for reuse in the same or same-owner equipment. Reclamation = an EPA-certified reclaimer restoring it to AHRI-700 spec, the only path that makes refrigerant legal to resell. The distinction is the backbone of where every legal pound of R-22 comes from today.
About the numbers. GWP figures are 100-year values from IPCC AR4 (the basis EPA uses for AIM Act accounting) unless shown as "<1"; other assessments differ slightly. ODP values follow EPA's Class I/II listings; blend ODPs are approximate. Glide, oil, and pressure notes are typical field values — the manufacturer's SDS, the nameplate, and the current regs always win. Rules summarized as of mid-2026 and focused on US federal law; states add their own. Reference material, not legal or engineering advice.