Heat Pump or AC: How to Tell from the Label
If the yellow EnergyGuide label lists an HSPF or HSPF2 rating, the unit is a heat pump, a maker's 2025 guide says. Air conditioners and heat pumps both carry a SEER or SEER2 cooling rating, the seasonal energy efficiency ratio. Only a heat pump lists HSPF, the heating seasonal performance factor.
Another maker puts the difference simply: a heat pump “can provide both heating and cooling, while a standard air conditioner provides cooling only.” Both sit outside, so read the labels on the outdoor unit first.
What Each Label Tells You
| Where to look | Heat pump if | Source |
|---|---|---|
| Yellow EnergyGuide label | It lists HSPF or HSPF2 as well as SEER or SEER2 | Trane guide; Carrier guide |
| Nameplate or rating plate on the outdoor unit | Some makers print the words “heat pump” on it | Trane guide |
| Model number on the rating plate (Carrier) | It starts with 25 (R-410A refrigerant) or 27 (R-454B refrigerant) | Carrier guide |
| Thermostat | It has an Em Heat (EMER) or Aux Heat (AUX) setting, the switches for backup heat | Trane guide; Carrier guide |
The Federal Label Rule
The Federal Trade Commission's labeling rule, 16 CFR 305.20, sets what an EnergyGuide label for a central air conditioner or heat pump shows. Paragraph (g)(5) calls for the SEER2 for the cooling function and, “for the heating function,” the HSPF2. Carrier's guide says the same in plain terms: “Air conditioners only display cooling efficiency metrics.”
Reading a Carrier Model Number
Carrier's guide says its heat pumps that use R-410A refrigerant start with “25” and those that use R-454B start with “27”. Carrier's 2019 service manual lists 24 as an air conditioner and 25 as a heat pump. Carrier puts the rating plate “generally on the back of the cabinet, above the service-valve connections,” apart from the EnergyGuide label.
If There Is No Label
- Copy the model number and the maker's name from the nameplate. Trane's heat pump guide says it is likely on the top or side of the outdoor unit.
- Search the maker's name and model number online. Trane and Carrier both say the result will show if it is a heat pump or an air conditioner.
- In cold weather, set the thermostat to heat and go outside. Trane says: “If the outdoor unit kicks on, it's a heat pump. An AC unit will remain silent.”
The same rating plate gives the unit's size and build date: AC tonnage from the model number and the Carrier date code.
Sources
- Trane, How Do I Know If I Have a Heat Pump? (published 2024-11-04, updated 2025-06-30): https://www.trane.com/residential/en/resources/troubleshooting/heat-pumps/how-do-i-know-if-i-have-a-heat-pump/
- Carrier, How Do I Know If I Have A Heat Pump? (undated page): https://www.carrier.com/us/en/residential/hvac-resources/heat-pumps/how-do-i-know-if-i-have-a-heat-pump/
- Federal Trade Commission, 16 CFR 305.20, Labeling for central air conditioners, heat pumps, and furnaces, paragraph (g)(5) (eCFR, up to date as of 10/29/2026): https://www.ecfr.gov/current/title-16/chapter-I/subchapter-C/part-305/subject-group-ECFR2d6e89d762242b4/section-305.20
- Carrier, service manual 24-25-9SM, edition date 09/19 (PDF), “Air Conditioner and Heat Pump Model Number Nomenclature”: https://www.shareddocs.com/hvac/docs/1009/Public/03/24-25-9SM.pdf