Replacing Your AC in Arizona: SEER2 Rules, New Refrigerants and What to Ask

If you replace a central air conditioner in Arizona, the new system must meet the federal Southwest efficiency standard, which is based on the date it is installed, not the date it was built. New systems now also use lower impact refrigerants such as R-454B or R-32 instead of R-410A. Your existing working system does not have to be replaced.

I get asked about air conditioners almost as often as I get asked about neighborhoods. In the Valley, the AC is not a luxury feature, it is the system that makes a house livable from late spring into fall. So when buyers see an older unit on an inspection report, or a homeowner gets a replacement quote with a lot of new terms in it, the questions come fast.

Why fall is a good time to think about your AC

Most of us only think about the AC when it quits on a hot afternoon. By late October the heavy cooling season is behind us, and that makes it a calmer time to have a system checked, compare quotes, or plan a replacement without the pressure of a 110 degree house. If your system struggled this past summer, now is the time to find out why.

What the Southwest efficiency rule means for Arizona homes

The U.S. Department of Energy set new minimum efficiency standards for central air conditioners and heat pumps that took effect January 1, 2023. The country is split into regions, and Arizona is in the hot-dry Southwest region along with California, Nevada and New Mexico.

A few points matter most for homeowners here:

• It is based on installation. In the Southwest, DOE says units installed on or after January 1, 2023 must meet the regional standard. In the North region the rule is tied to manufacture date instead, but that is not how it works here.
• The minimum is higher here than in much of the country. For a typical home-size split system (under 45,000 Btu per hour, which covers most residential units), DOE's Southwest minimum is 14.3 SEER2, compared with 13.4 SEER2 in the North region. The Southwest also has a separate EER2 requirement that measures efficiency at peak heat, which makes sense for our summers.
• SEER2 is not the same as the old SEER. DOE explains that SEER2 comes from an updated test meant to better reflect real-world installation, and the two numbers are not directly comparable. If an older system is labeled 14 SEER and a new one is labeled 14.3 SEER2, you cannot line them up one to one.
• It does not force you to replace a working unit. The standard applies to systems being installed, including replacement outdoor units. Nothing in DOE's guidance says a homeowner has to swap out a system that is still running.

The refrigerant change: R-410A, R-454B and R-32

The other big change is the refrigerant inside the system. Under the EPA's Technology Transitions rule, new residential air conditioning and heat pump systems made or imported starting January 1, 2025 have to use refrigerants below the rule's global warming potential limit. That is why you now see equipment built for refrigerants like R-454B and R-32 instead of R-410A, which was the standard for years.

The original rule also set a January 1, 2026 deadline to install older R-410A equipment. In May 2026, the EPA finalized a change that removed that installation date for equipment made or imported before January 1, 2025, so that existing inventory can be installed until supply runs out. The 2025 manufacturing cutoff did not change.

What this means for you: if you are getting quotes, ask which refrigerant each system uses. A contractor may offer a leftover R-410A unit or a newer R-454B or R-32 unit, and it helps to know which one you are comparing. If you already have a working R-410A system, the EPA rule is about making and installing new equipment, so a system you already own is not something you need to rush to replace because of it.

Simple maintenance that helps in our climate

The U.S. Department of Energy's homeowner guidance lines up with what I see in Valley homes every week:

• Filters first. DOE calls filter care the most important maintenance task and says to clean or replace it every month or two during cooling season, more often with pets or dusty conditions. DOE says a clean filter can cut energy use by 5% to 15%. Our cooling season is long, so mark your calendar.
• Give the outdoor unit room. DOE recommends keeping at least 2 feet clear around the condenser. In Arizona yards that usually means trimming back oleanders, bougainvillea and anything planted too close, and keeping leaves and mower debris away.
• Have a professional check what you cannot see. DOE's list for a technician includes the refrigerant level, leak testing, duct leaks, airflow across the coil, electrical connections, and thermostat accuracy.

Buying or selling a home with an older AC

When I represent buyers, the AC is one of the first things I want the home inspector to look at closely. The inspection period is the time to learn the age and condition of the system and decide whether to ask for a repair, a credit, or a further evaluation by an HVAC company. I walk through that process in my guide to getting through the Arizona inspection period.

For sellers, having service records and the install date handy makes buyers more comfortable. You can read more about how I approach a sale on my selling page, and if you are still deciding where to land, my cost of living guide for Phoenix covers the bigger picture of owning here.

Questions people ask

Do I have to replace my old AC because of the new rules?
No. The DOE efficiency standard and the EPA refrigerant rule apply to new equipment being made and installed. A working system you already own can keep running.

What is the minimum SEER2 for a new AC in Arizona?
For a typical home split system under 45,000 Btu per hour, DOE's Southwest minimum is 14.3 SEER2, plus a separate EER2 requirement. Larger systems have slightly different numbers.

Can a contractor still install an R-410A system?
Yes, if the equipment was made or imported before January 1, 2025. The EPA's May 2026 final rule removed the installation deadline for that older inventory, so it can be installed until supply runs out. It still has to meet the Southwest efficiency standard.

Terry Day, REALTOR®, DeLex Realty, 10115 E Bell Rd, Scottsdale, AZ 85260.