What kind of Freon do old AC units use?
Most older residential air conditioners relied on R-22 Freon, with some very early systems using R-12. Today, R-22 is being phased out and is largely unavailable for new applications, while R-12 is mostly banned for use in new equipment. If you own an older AC unit, it’s likely to run on one of these refrigerants, which affects servicing and potential replacement decisions.
Historical context of Freon refrigerants
The term Freon has long been used as a generic label for refrigerants manufactured by DuPont and allied companies. Over the decades, environmental regulation and technological advances shifted which substances were used in air conditioning systems. The Montreal Protocol and subsequent U.S. and global rules phased out many ozone-depleting refrigerants, driving changes from CFCs to HCFCs and eventually to HFCs and low-GWP options.
Key refrigerants in older systems
To understand what you might encounter in older equipment, here is a quick reference to the refrigerants commonly found in older air conditioners.
- R-22 (chlorodifluoromethane), also known as Freon 22 — the dominant refrigerant for many home and small commercial systems built from the 1980s through the early 2000s.
- R-12 (dichlorodifluoromethane), an older refrigerant used in some pre-1990s systems and primarily found in very old equipment or certain automotive applications; its use in new equipment has been banned, and handling is tightly regulated.
In practice, most mid- to late-20th-century residential equipment relied on R-22, while R-12 was more common in older or specialized applications. As environmental rules tightened, R-12 was phased out of new equipment and R-22 became the standard for decades before its own phase-down began.
Practical guidance for homeowners with old units
If your cooling system is older, here’s what you should know about refrigerants and what options exist today.
- R-22 in servicing: Production and import of R-22 for use in new equipment stopped years ago in many regions, and sales are largely restricted to reclaimed or recycled R-22 for servicing existing units. Costs can be high and availability limited.
- R-12 considerations: R-12 is largely banned for new equipment and its use is tightly regulated. If you have an R-12 system, the typical path is replacement rather than attempting to retrofit with R-12.
- Retrofits and replacements: Some older systems can be retrofitted to a different refrigerant, but this is increasingly discouraged or limited due to efficiency, safety, and regulatory concerns. Most experts recommend upgrading to a modern system using a low-GWP refrigerant.
- New equipment options: New residential air conditioners commonly use R-410A, and some newer models are transitioning to lower-GWP blends or single-component refrigerants such as R-32 in certain markets. Upgrading often yields better efficiency and lower environmental impact.
The guidance above reflects current regulatory and market realities: while you may be able to service an older R-22 system today, it is increasingly expensive and less practical than upgrading to a modern unit with a refrigerant designed for long-term availability and efficiency.
What to do if you own an old AC unit
For homeowners facing an aging system, here are the recommended steps to consider, based on current standards and best practices.
- Consult a licensed HVAC technician: If your unit uses R-22 or potentially R-12, have a professional confirm the refrigerant type, assess leak risks, and discuss servicing options and costs.
- Assess the cost-benefit of replacement: Because refrigerant supply and service costs for R-22 can be high, many households find that a mid- to high-efficiency replacement with a modern refrigerant is the economically and environmentally sensible choice.
- Understand regulatory constraints: Do not vent or release refrigerants — recovering and properly disposing of old refrigerants is required by law in many jurisdictions. Improper handling can lead to penalties and environmental harm.
- Future-proof your system: If you replace, choose a unit compatible with low-GWP refrigerants and consider efficiency ratings, system sizing, and potential rebates or incentives for energy-efficient equipment.
In practical terms, most households with a truly old AC unit will save time and money by planning a modern replacement rather than continuing to service an aging system with increasingly restricted refrigerants.
Bottom line
Old residential air conditioners typically used R-22 Freon, with some even older units using R-12. R-22 is being phased out for new production, and R-12 has been largely banned in modern equipment. If you own an older system, you’ll likely face higher servicing costs and limited refrigerant availability, making replacement with a modern, low-GWP refrigerant unit a common and prudent option.
Summary: The Freon in most older home AC units is R-22, a refrigerant under regulatory phase-down, while the oldest equipment may have used R-12. Today’s market favors upgrading to new equipment using low-GWP refrigerants, with professional guidance essential for any servicing or replacement decisions.
