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      12,000 BTU mini-split heat pump · 45M Series

      Carrier 37MAHAQ12AA3

      Very good cooling and heating efficiency for a 12,000 BTU mini-split heat pump, and certified for cold climates.

      Ranks #40 of 394 12,000 BTU mini-splits for cooling efficiency, and costs about $264 a year to run in a mixed climate like Atlanta.

      SEER2
      25.5 Cooling efficiency over a season
      Very good · beats 88%
      HSPF2
      11.6 Heating efficiency over a season
      Very good · beats 86%
      EER2
      13.5 Cooling efficiency on a 95°F day
      Very good · beats 74%
      Heat at 5°F
      12,000 BTU/h96% of its 47°F output
      Average · beats 48%

      A good fit if…

      • You want low cooling bills - its SEER2 beats 88% of mini-splits.
      • Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 12,000 BTU/h at 5°F.
      • It will heat most of the year - its HSPF2 beats 86% of mini-splits.
      • You want steady temperatures and quiet running - the compressor varies its speed.

      Think twice if…

      • Nothing stands out - its ratings have no weak spot for its class.

      Calculate my running cost

      Details

      Specifications12,000 BTU, R-454B
      General
      BrandCarrier
      Also sold asBryant, Midea, Payne, WeatherMaker
      Outdoor unit model37MAHAQ12AA3
      Series45M Series
      TypeMini-split heat pump
      Nominal size12,000 BTU
      CompressorVariable-speed units run longer at low powerContinuously variable
      RefrigerantR-454B
      Connected (smart) capableNo
      On the market sinceNovember 15, 2018
      Last certifiedJune 1, 2026
      Cooling
      SEER2Seasonal efficiency, higher is better25.5 (range 20.0-25.5)
      EER2Efficiency at 95°F outdoors12.0-13.5
      Cooling capacity12,000 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better10.2-11.6
      Capacity at 47°F12,000-12,500 BTU/h
      Capacity at 17°F9,600-12,000 BTU/h
      Capacity at 5°F11,300-12,000 BTU/h
      COP at 5°F2.0 = twice as efficient as a space heater1.80-2.00
      ENERGY STAR cold climateYes
      Heating output as it gets colder96% kept at 5°F

      Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with 45MAHAQ12XA3 at the standard test temperatures, in BTU/h:

      Certified matchups32 indoor units

      The same outdoor unit scores differently with each indoor unit. Ask your installer for the AHRI reference number of the exact system you are quoted.

      Indoor unitSEER2EER2HSPF2Heat @5°FAHRI ref.
      45MAHAQ12XA3 CARRIER · cold climate25.513.510.511,500215323744
      615AHAQ12XA3 BRYANT · cold climate25.513.510.511,500215323755
      D5MAHAQ12XA3 MIDEA · cold climate25.513.510.511,500215323788
      D5MAHAQ12XA3 PAYNE · cold climate25.513.510.511,500215323766
      D5MAHAQ12XA3 Weathermaker · cold climate25.513.510.511,500215323777
      D5MAHAQ12XA3 BRYANT · cold climate25.513.510.511,500218139564
      D5MAHAQ12XA3 CARRIER · cold climate25.513.510.511,500218139551
      45MBFAQ12XA3 CARRIER · cold climate25.012.710.611,300215323806
      45MBFAQ12XA3 MIDEA · cold climate25.012.710.611,300215324050
      45MBFAQ12XA3 BRYANT · cold climate25.012.710.611,300215323867
      45MBFAQ12XA3 PAYNE · cold climate25.012.710.611,300215323928
      45MBFAQ12XA3 Weathermaker · cold climate25.012.710.611,300215323989
      45MCCAQ12XA3 CARRIER · cold climate23.013.010.211,500215323804
      45MCCAQ12XA3 BRYANT · cold climate23.013.010.211,500215323865
      45MCCAQ12XA3 PAYNE · cold climate23.013.010.211,500215323926
      45MCCAQ12XA3 Weathermaker · cold climate23.013.010.211,500215323987
      45MCCAQ12XA3 MIDEA · cold climate23.013.010.211,500215324048
      45MBCAQ12XA3 CARRIER · cold climate22.312.711.611,500215323805
      45MBCAQ12XA3 BRYANT · cold climate22.312.711.611,500215323866
      45MBCAQ12XA3 PAYNE · cold climate22.312.711.611,500215323927
      45MBCAQ12XA3 Weathermaker · cold climate22.312.711.611,500215323988
      45MBCAQ12XA3 MIDEA · cold climate22.312.711.611,500215324049
      45MBDAQ12XH3 CARRIER · cold climate20.212.010.612,000215323808
      45MBDAQ12XH3 BRYANT · cold climate20.212.010.612,000215323869
      45MBDAQ12XH3 PAYNE · cold climate20.212.010.612,000215323930
      45MBDAQ12XH3 Weathermaker · cold climate20.212.010.612,000215323991
      45MBDAQ12XH3 MIDEA · cold climate20.212.010.612,000215324052
      45MBDAQ12XA3 CARRIER · cold climate20.012.010.211,800215323807
      45MBDAQ12XA3 BRYANT · cold climate20.012.010.211,800215323868
      45MBDAQ12XA3 PAYNE · cold climate20.012.010.211,800215323929
      45MBDAQ12XA3 Weathermaker · cold climate20.012.010.211,800215323990
      45MBDAQ12XA3 MIDEA · cold climate20.012.010.211,800215324051
      Yearly running cost in 10 large cities$222-$642

      At each state's average electricity price and the city's typical heating and cooling hours.

      Questions5
      What is the SEER2 rating of the Carrier 37MAHAQ12AA3?
      The Carrier 37MAHAQ12AA3 is rated at up to 25.5 SEER2 and 13.5 EER2 for cooling and up to 11.6 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with; across its 32 certified matchups SEER2 ranges from 20.0-25.5.
      Is the Carrier 37MAHAQ12AA3 good for cold climates?
      Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 12,000 BTU/h at 5°F with a COP of 2.00, so it is still 2.0 times as efficient as electric resistance heat at that temperature.
      How much does the Carrier 37MAHAQ12AA3 cost to run per year?
      At its rated efficiency it costs about $222-$642 a year in electricity in large U.S. cities, depending on climate and local rates - for example $280 in Phoenix and $541 in Minneapolis. The calculator on this page works it out for your city and compares it with your current system.
      Which indoor units work with the Carrier 37MAHAQ12AA3?
      ENERGY STAR lists 32 certified combinations for this outdoor unit. The highest-rated ones use CARRIER 45MAHAQ12XA3, BRYANT 615AHAQ12XA3, MIDEA D5MAHAQ12XA3.
      What refrigerant does the Carrier 37MAHAQ12AA3 use?
      It uses R-454B.

      Running cost and savings

      Pre-filled with this model. Pick your city and what you heat with today; everything else is optional.

      Heat pump $282/yrYou save $337/yrSee details ↓
      1. Where you live
      Adjust heating and cooling hours

      Filled in from your city's climate. Change them if you run the system much more or less than usual.

      2. The heat pump Carrier 37MAHAQ12AA3
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $282
      Current system, per year
      $619
      You save per year
      $337
      Payback
      13.3 years
      Net after 10 years
      -$1,128

      Cooling $166Heating $116Electricity used: 1,759 kWhSaved vs. a minimum-efficiency heat pump: $193

      Estimates use the unit's rated SEER2 and HSPF2, full-load hours derived from NOAA 1991-2020 degree days, average residential electricity prices from the U.S. EIA (12 months to July 2026) and fuel prices from EIA (2025 for natural gas, week of 2026-10-05 for propane and heating oil). Very cold days that need backup heat are not modelled. Federal minimum for comparison: 14.3 SEER2 / 7.5 HSPF2.

      Similar 12,000 BTU models

      See all 394 12,000 BTU mini-splits, ranked

      Source: ENERGY STAR Certified Heat Pumps (U.S. EPA), certification of June 1, 2026. How we use the data.