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      1.5-ton central heat pump · 45M Series

      Carrier 37MUHAQ18AA3

      Very good cooling efficiency and excellent heating efficiency for a 1.5-ton central heat pump, and certified for cold climates.

      Ranks #7 of 170 1.5 ton central heat pumps for cooling efficiency, and costs about $474 a year to run in a mixed climate like Atlanta.

      SEER2
      19.3 Cooling efficiency over a season
      Very good · beats 89%
      HSPF2
      10.8 Heating efficiency over a season
      Excellent · beats 98%
      EER2
      12.1 Cooling efficiency on a 95°F day
      Very good · beats 74%
      Heat at 5°F
      19,600 BTU/h103% of its 47°F output
      Average · beats 65%

      A good fit if…

      • You want low cooling bills - its SEER2 beats 89% of central heat pumps.
      • Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 19,600 BTU/h at 5°F.
      • It will heat most of the year - its HSPF2 beats 98% of central heat pumps.
      • 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

      Specifications1.5 ton, R-454B
      General
      BrandCarrier
      Also sold asBryant, Payne, WeatherMaker, Midea, PAYNE HEATING AND COOLING
      Outdoor unit model37MUHAQ18AA3
      Series45M Series
      TypeCentral heat pump
      Nominal size1.5 ton
      CompressorVariable-speed units run longer at low powerContinuously variable
      RefrigerantR-454B
      Connected (smart) capableNo
      On the market sinceNovember 15, 2018
      Last certifiedApril 21, 2026
      Cooling
      SEER2Seasonal efficiency, higher is better19.3 (range 15.5-19.3)
      EER2Efficiency at 95°F outdoors11.5-12.5
      Cooling capacity18,000-18,400 BTU/h
      Heating
      HSPF2Seasonal efficiency, higher is better9.5-10.8
      Capacity at 47°F18,000-20,400 BTU/h
      Capacity at 17°F14,700-15,400 BTU/h
      Capacity at 5°F18,000-19,600 BTU/h
      COP at 5°F2.0 = twice as efficient as a space heater1.98-2.12
      ENERGY STAR cold climateYes
      Heating output as it gets colder103% kept at 5°F

      Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with D5MUWAQ18XA3 at the standard test temperatures, in BTU/h:

      Certified matchups33 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.
      D5MUWAQ18XA3 · cold climate19.312.110.819,600217730629
      D5MUWAQ18XA3 · cold climate19.312.110.819,600217730645
      D5MUWAQ18XA3 · cold climate19.312.110.819,600217730661
      D5MUWAQ18XA3 · cold climate19.312.110.819,600217730677
      D5MUWAQ18XA3 · cold climate19.312.110.819,600217730613
      45MUHAQ24XX3 · cold climate19.012.510.218,600215318761
      45MUHAQ24XX3 · cold climate19.012.510.218,600215318789
      45MUHAQ24XX3 · cold climate19.012.510.218,600215318817
      45MUHAQ24XX3 · cold climate19.012.510.218,600215318845
      45MUHAQ24XX3 · cold climate19.012.510.218,600215318873
      D5FUHAH24XAK · cold climate19.012.510.218,600217557332
      D5FUHAH24XAK · cold climate19.012.510.218,600217557341
      D5FUHAH24XAK · cold climate19.012.510.218,600217730693
      D5FUHAH24XAK · cold climate19.012.510.218,600217730699
      D5FUHAH24XAK · cold climate19.012.510.218,600217730705
      45MUAAQ18XX3 · cold climate19.012.59.818,000215318747
      45MUAAQ18XX3 · cold climate19.012.59.818,000215318775
      45MUAAQ18XX3 · cold climate19.012.59.818,000215318803
      45MUAAQ18XX3 · cold climate19.012.59.818,000215318831
      45MUAAQ18XX3 · cold climate19.012.59.818,000215318859
      45MULAQ24XAX · cold climate16.111.79.518,000217456380
      45MULAQ24XBX · cold climate16.111.79.518,000217456381
      45MULAQ24XAX · cold climate16.111.79.518,000217456352
      45MULAQ24XBX · cold climate16.111.79.518,000217456353
      45MULAQ24XBX · cold climate16.111.79.518,000217456409
      45MULAQ24XAX · cold climate16.111.79.518,000217456296
      45MULAQ24XBX · cold climate16.111.79.518,000217456297
      45MULAQ24XAX · cold climate16.111.79.518,000217456324
      45MULAQ24XBX · cold climate16.111.79.518,000217456325
      45MULAQ24XAX · cold climate16.111.79.518,000217456408
      FT5ANXB24L · cold climate15.511.59.518,300216638494
      FT5ANXB24L · cold climate15.511.59.518,300216640205
      PF5TNXB24L · cold climate15.511.59.518,300216640209
      Yearly running cost in 10 large cities$438-$1,123

      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 37MUHAQ18AA3?
      The Carrier 37MUHAQ18AA3 is rated at up to 19.3 SEER2 and 12.1 EER2 for cooling and up to 10.8 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with; across its 33 certified matchups SEER2 ranges from 15.5-19.3.
      Is the Carrier 37MUHAQ18AA3 good for cold climates?
      Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 19,600 BTU/h at 5°F with a COP of 2.12, so it is still 2.1 times as efficient as electric resistance heat at that temperature.
      How much does the Carrier 37MUHAQ18AA3 cost to run per year?
      At its rated efficiency it costs about $438-$1,123 a year in electricity in large U.S. cities, depending on climate and local rates - for example $533 in Phoenix and $933 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 37MUHAQ18AA3?
      ENERGY STAR lists 33 certified combinations for this outdoor unit. The highest-rated ones use D5MUWAQ18XA3, 45MUHAQ24XX3, D5FUHAH24XAK.
      What refrigerant does the Carrier 37MUHAQ18AA3 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 $525/yrYou save $419/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 37MUHAQ18AA3
      3. What it replaces
      4. Price replace the example with your quote
      Heat pump, per year
      $525
      Current system, per year
      $944
      You save per year
      $419
      Payback
      16.7 years
      Net after 10 years
      -$2,808

      Cooling $328Heating $197Electricity used: 3,283 kWhSaved vs. a minimum-efficiency heat pump: $201

      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 1.5 ton models

      See all 170 1.5 ton central heat pumps, ranked

      Source: ENERGY STAR Certified Heat Pumps (U.S. EPA), certification of April 21, 2026. How we use the data.