We found no government or standards-body source that recommends a SEER2 rating for Phoenix, and we do not pick one here. What does exist is a set of federal minimums for the Southwest, an EER2 rule tied to a 95°F rating condition, and SRP's rebate tiers. This guide explains what each one requires and rewards, as of October 2026. It does not recommend brands.
Federal SEER2 and EER2 minimums in the Southwest
Under 10 CFR 430.32, split-system and single-package air conditioners "that are installed on or after January 1, 2023, in the southeast or southwest must have a Seasonal Energy Efficiency Ratio 2 and a Energy Efficiency Ratio 2 not less than" the levels in its regional table. The rule says the Southwest "includes the States of Arizona, California, Nevada, and New Mexico." These minimums come from the federal rule, not from Arizona. The regional rule depends on where and when the system is installed.
| Split-system AC size | National minimum (units manufactured on or after January 1, 2023) | Southwest minimum SEER2 | Southwest minimum EER2 |
|---|---|---|---|
| Under 45,000 Btu/hr | 13.4 SEER2 | 14.3 | 11.7 if rated below 15.2 SEER2; 9.8 if rated 15.2 SEER2 or higher |
| 45,000 Btu/hr or more | Not covered here | 13.8 | 11.2/9.8, as listed in the rule |
Federal minimums for split-system ACs under 45,000 Btu/hr
| National minimum (manufactured on or after Jan. 1, 2023) | 13.4 SEER2 |
|---|---|
| Southwest minimum | 14.3 SEER2 |
| Southwest minimum, rated below 15.2 SEER2 | 11.7 EER2 |
| Southwest minimum, rated 15.2 SEER2 or higher | 9.8 EER2 |
The rule's footnote explains the two EER2 levels for smaller systems: "The 11.7 EER2 standard applies to products with a certified SEER2 less than 15.2. The 9.8 EER2 standard applies to products with a certified SEER2 greater than or equal to 15.2." The rule also says, "Any model of outdoor unit that has a certified combination with a rating below the applicable standard level(s) for a region cannot be installed in that region."
The regional rule names split-system and single-package air conditioners. Split-system heat pumps manufactured on or after January 1, 2023 have a national minimum of 14.3 SEER2 and 7.5 HSPF2. Our guide to SEER2 ratings covers the national and regional minimums in more detail.
What EER2 measures
ENERGY STAR's Version 6.2 requirements define it this way: "EER2 is the ratio of the average rate of space cooling delivered to the average rate of electrical energy consumed by the air conditioner or heat pump. This ratio is expressed in Btu per Wh (Btu/Wh)."
The federal regional table adds a test condition. Its footnote says, "EER refers to the energy efficiency ratio at a standard rating of 95 °F dry bulb outdoor temperature." The footnote says "EER," though the table's column is labeled EER2. We found no DOE, eCFR or ENERGY STAR statement, in the agency's own voice, that explains why EER2 matters in hot weather.
Why the Southwest kept an EER rule
DOE's 2017 direct final rule records the views of participants in its CAC/HP Working Group. It reports: "Other parties were firm about keeping EER because it would mitigate peak load issues and improve the health of the utility grid. They added that EER can be a better descriptor than SEER for energy use in certain regions, such as the Southwest." These were arguments made by working-group participants, which DOE recorded. They are not a DOE finding.
DOE's rule then describes the outcome. "Eventually, the CAC/HP Working Group decided to retain the current minimum EER requirements for split-system air conditioners and single- package air conditioners in the Southwest region with a SEER less than 15.2 and a relaxed EER requirement for split-system air conditioners and single-package air conditioners in the Southwest region with a SEER greater than 15.2." The 2017 rule used the older SEER and EER metrics. Today's eCFR table sets its EER2 split at 15.2 SEER2.
SRP Cool Cash rebate tiers
SRP's Cool Cash rebate pays per ton of capacity. Every tier has the same 15.2 SEER2 floor, and the tiers differ by compressor type. The table shows SRP's amounts as of October 2026.
| SRP tier and compressor type | Minimum SEER2 | Heat pump rebate per ton | AC rebate per ton |
|---|---|---|---|
| Good: Single-stage | 15.2 or higher | $75 | $75 |
| Better: Multi-stage | 15.2 or higher | $150 | $150 |
| Best: Variable-capacity | 15.2 or higher | $225 | $225 |
| Best: Inverter-driven mini split | 15.2 or higher | $225 | Not listed |
SRP says, "All qualifying equipment must be listed in the AHRI Verified Directories as meeting or exceeding the efficiency minimums." AHRI is the Air-Conditioning, Heating, and Refrigeration Institute, the industry's trade association. The system must be "installed by a contractor licensed in Arizona to install residential air-conditioning systems before April 30, 2027." It must replace or supplement "an existing central heat pump or central AC."
For single-stage systems, SRP requires Manual J load calculations with your application, "otherwise, your application will be delayed or denied." It says, "Load calculations are not required for multi-stage or variable-capacity systems." SRP explains the sizing concern: "A unit that's too big for your home can lead to expensive energy bills and may cause 'short cycling,' which will wear the unit out."
SRP's savings estimates and their assumptions
SRP publishes savings estimates for each compressor type. Its footnote says: "Results will vary. Assumes replacement of existing 11 SEER system, $0.11/kWh and 2,141 cooling hours." These are SRP's assumptions, not measured results for your home.
| SRP compressor type (SEER / SEER2 in SRP's heading) | 3 tons: 1 year / 15 years | 4 tons: 1 year / 15 years | 5 tons: 1 year / 15 years |
|---|---|---|---|
| Single-stage (16 / 15.2) | $240 / $3,600 | $320 / $4,800 | $400 / $6,000 |
| Multi-stage (18 / 17.0) | $300 / $4,500 | $400 / $6,000 | $500 / $7,500 |
| Variable-capacity (21 / 20.0) | $370 / $5,500 | $490 / $7,350 | $610 / $9,150 |
SRP's estimated first-year savings for a 4-ton system, by compressor type
- Single-stage (15.2 SEER2)$320
- Multi-stage (17.0 SEER2)$400
- Variable-capacity (20.0 SEER2)$490
SRP pairs each SEER2 figure with an older SEER figure in its table headings. We found no DOE sentence that gives a general SEER-to-SEER2 conversion factor, so we do not convert ratings ourselves.
APS offers as of October 2026
APS's Cool Rewards program is for smart thermostats. APS says customers who buy and enroll a smart thermostat "will receive their $50 enrollment bill credit per smart thermostat." That is a thermostat program, not an AC or heat pump equipment rebate.
We found no APS AC rebate page as of October 2026. We are not saying APS has ended its rebates. Ask APS what it offers before you buy.
ENERGY STAR no longer certifies central ACs
ENERGY STAR says, "On February 1, 2026, EPA sunset the ENERGY STAR specification for central air conditioners." That means ENERGY STAR no longer has a current central AC specification to compare a quote against.
What the rules and rebates reward in Phoenix
The federal rule sets a floor of 14.3 SEER2 for split ACs under 45,000 Btu/hr installed in the Southwest. It also sets an EER2 minimum that drops from 11.7 to 9.8 once a system is rated 15.2 SEER2 or higher. SRP's rebate starts at that same 15.2 SEER2 level and pays more per ton for multi-stage and variable-capacity compressors. Programs change, so confirm the current terms with your utility before you sign a contract.
If you are deciding whether to replace an older system, our guide to how long an AC lasts in Arizona covers the lifespan estimates and Phoenix weather data. Our guide to the R-410A phase-out covers the refrigerant rules.