What is the SEER2 rating of the Carrier 37MAHAQ18AA3?

The Carrier 37MAHAQ18AA3 is rated at up to 21.5 SEER2 and 12.5 EER2 for cooling and up to 12.4 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with; across its 42 certified matchups SEER2 ranges from 18.0-21.5.

Is the Carrier 37MAHAQ18AA3 good for cold climates?

Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 18,000 BTU/h at 5°F with a COP of 2.20, so it is still 2.2 times as efficient as electric resistance heat at that temperature.

How much does the Carrier 37MAHAQ18AA3 cost to run per year?

At its rated efficiency it costs about $371-$973 a year in electricity in large U.S. cities, depending on climate and local rates - for example $455 in Phoenix and $811 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 37MAHAQ18AA3?

ENERGY STAR lists 42 certified combinations for this outdoor unit. The highest-rated ones use CARRIER 45MAHAQ18XA3, BRYANT 615AHAQ18XA3, PAYNE D5MAHAQ18XA3.

18,000 BTU mini-split heat pump · 45M Series

Carrier 37MAHAQ18AA3

Below average cooling efficiency and excellent heating efficiency for a 18,000 BTU mini-split heat pump, and certified for cold climates.

Ranks #257 of 465 18,000 BTU mini-splits for cooling efficiency, and costs about $409 a year to run in a mixed climate like Atlanta.

SEER2: 21.5 Cooling efficiency over a season
Below average · beats 39%
HSPF2: 12.4 Heating efficiency over a season
Excellent · beats 93%
EER2: 12.5 Cooling efficiency on a 95°F day
Average · beats 44%
Heat at 5°F: 18,000 BTU/h100% of its 47°F output
Very good · beats 78%

A good fit if…

Your winters get properly cold - it is ENERGY STAR cold-climate certified, with 18,000 BTU/h at 5°F.
It will heat most of the year - its HSPF2 beats 93% of mini-splits.
You want steady temperatures and quiet running - the compressor varies its speed.
You want a choice of indoor units - 42 certified pairings.

Think twice if…

Cooling cost matters most - its SEER2 is below average for mini-splits.

Calculate my running cost

Details

Specifications18,000 BTU, R-454B

General
Brand	Carrier
Also sold as	Bryant, Payne, WeatherMaker, Midea
Outdoor unit model	37MAHAQ18AA3
Series	45M Series
Type	Mini-split heat pump
Nominal size	18,000 BTU
CompressorVariable-speed units run longer at low power	Continuously variable
Refrigerant	R-454B
Connected (smart) capable	No
On the market since	November 15, 2018
Last certified	June 1, 2026
Cooling
SEER2Seasonal efficiency, higher is better	21.5 (range 18.0-21.5)
EER2Efficiency at 95°F outdoors	12.0-12.6
Cooling capacity	16,000-18,000 BTU/h
Heating
HSPF2Seasonal efficiency, higher is better	10.1-12.4
Capacity at 47°F	17,000-20,000 BTU/h
Capacity at 17°F	14,000-18,000 BTU/h
Capacity at 5°F	17,000-18,000 BTU/h
COP at 5°F2.0 = twice as efficient as a space heater	1.86-2.20
ENERGY STAR cold climate	Yes

Heating output as it gets colder100% kept at 5°F

Every heat pump delivers less heat as the outdoor temperature drops. Certified output of its matchup with 45MAHAQ18XA3 at the standard test temperatures, in BTU/h:

Certified matchups42 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 unit	SEER2	EER2	HSPF2	Heat @5°F	AHRI ref.
45MAHAQ18XA3 CARRIER · cold climate	21.5	12.5	11.0	18,000	215323745
615AHAQ18XA3 BRYANT · cold climate	21.5	12.5	11.0	18,000	215323756
D5MAHAQ18XA3 PAYNE · cold climate	21.5	12.5	11.0	18,000	215323767
D5MAHAQ18XA3 Weathermaker · cold climate	21.5	12.5	11.0	18,000	215323778
D5MAHAQ18XA3 MIDEA · cold climate	21.5	12.5	11.0	18,000	215323789
D5MAHAQ18XA3 BRYANT · cold climate	21.5	12.5	11.0	18,000	218139565
D5MAHAQ18XA3 CARRIER · cold climate	21.5	12.5	11.0	18,000	218139552
45MCCAQ18XA3 CARRIER · cold climate	20.7	12.5	12.2	17,500	215323809
45MCCAQ18XA3 BRYANT · cold climate	20.7	12.5	12.2	17,500	215323870
45MCCAQ18XA3 PAYNE · cold climate	20.7	12.5	12.2	17,500	215323931
45MCCAQ18XA3 Weathermaker · cold climate	20.7	12.5	12.2	17,500	215323992
45MCCAQ18XA3 MIDEA · cold climate	20.7	12.5	12.2	17,500	215324053
45MCFAQ18XA3 CARRIER · cold climate	20.5	12.6	10.3	17,000	215323812
45MCFAQ18XA3 BRYANT · cold climate	20.5	12.6	10.3	17,000	215323873
45MCFAQ18XA3 PAYNE · cold climate	20.5	12.6	10.3	17,000	215323934
45MCFAQ18XA3 Weathermaker · cold climate	20.5	12.6	10.3	17,000	215323995
45MCFAQ18XA3 MIDEA · cold climate	20.5	12.6	10.3	17,000	215324056
45MBFAQ16XA3 CARRIER · cold climate	20.2	12.5	10.3	17,500	215323811
45MBFAQ16XA3 BRYANT · cold climate	20.2	12.5	10.3	17,500	215323872
45MBFAQ16XA3 PAYNE · cold climate	20.2	12.5	10.3	17,500	215323933
45MBFAQ16XA3 Weathermaker · cold climate	20.2	12.5	10.3	17,500	215323994
45MBFAQ16XA3 MIDEA · cold climate	20.2	12.5	10.3	17,500	215324055
45MBCAQ18XA3 CARRIER · cold climate	20.0	12.5	12.4	17,000	215323810
45MBCAQ18XA3 BRYANT · cold climate	20.0	12.5	12.4	17,000	215323871
45MBCAQ18XA3 PAYNE · cold climate	20.0	12.5	12.4	17,000	215323932
45MBCAQ18XA3 Weathermaker · cold climate	20.0	12.5	12.4	17,000	215323993
45MBCAQ18XA3 MIDEA · cold climate	20.0	12.5	12.4	17,000	215324054
45MBDAQ18XH3 CARRIER · cold climate	18.5	12.1	11.1	18,000	215323814
45MBDAQ18XH3 BRYANT · cold climate	18.5	12.1	11.1	18,000	215323875
45MBDAQ18XH3 PAYNE · cold climate	18.5	12.1	11.1	18,000	215323936
45MBDAQ18XH3 Weathermaker · cold climate	18.5	12.1	11.1	18,000	215323997
45MBDAQ18XH3 MIDEA · cold climate	18.5	12.1	11.1	18,000	215324058
45MBAAQ18XB3 · cold climate	18.2	12.0	10.1	18,000	215318764
45MBAAQ18XB3 · cold climate	18.2	12.0	10.1	18,000	215318820
45MBAAQ18XB3 · cold climate	18.2	12.0	10.1	18,000	215318848
45MBAAQ18XB3 · cold climate	18.2	12.0	10.1	18,000	215318876
45MBAAQ18XB3 · cold climate	18.2	12.0	10.1	18,000	215318792
45MBDAQ18XA3 CARRIER · cold climate	18.0	12.0	10.8	18,000	215323813
45MBDAQ18XA3 BRYANT · cold climate	18.0	12.0	10.8	18,000	215323874
45MBDAQ18XA3 PAYNE · cold climate	18.0	12.0	10.8	18,000	215323935
45MBDAQ18XA3 Weathermaker · cold climate	18.0	12.0	10.8	18,000	215323996
45MBDAQ18XA3 MIDEA · cold climate	18.0	12.0	10.8	18,000	215324057

Yearly running cost in 10 large cities$371-$973

Phoenix, AZ$455/yr
Miami, FL$371/yr
Houston, TX$408/yr
Atlanta, GA$409/yr
Los Angeles, CA$397/yr
New York, NY$973/yr
Chicago, IL$789/yr
Denver, CO$655/yr
Seattle, WA$402/yr
Minneapolis, MN$811/yr

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 37MAHAQ18AA3?: The Carrier 37MAHAQ18AA3 is rated at up to 21.5 SEER2 and 12.5 EER2 for cooling and up to 12.4 HSPF2 for heating. The exact figure depends on the indoor unit it is paired with; across its 42 certified matchups SEER2 ranges from 18.0-21.5.
Is the Carrier 37MAHAQ18AA3 good for cold climates?: Yes. At least one certified matchup meets the ENERGY STAR cold-climate criteria, delivering up to 18,000 BTU/h at 5°F with a COP of 2.20, so it is still 2.2 times as efficient as electric resistance heat at that temperature.
How much does the Carrier 37MAHAQ18AA3 cost to run per year?: At its rated efficiency it costs about $371-$973 a year in electricity in large U.S. cities, depending on climate and local rates - for example $455 in Phoenix and $811 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 37MAHAQ18AA3?: ENERGY STAR lists 42 certified combinations for this outdoor unit. The highest-rated ones use CARRIER 45MAHAQ18XA3, BRYANT 615AHAQ18XA3, PAYNE D5MAHAQ18XA3.
What refrigerant does the Carrier 37MAHAQ18AA3 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 $450/yrYou save $459/yrSee details ↓

1. Where you live

StateCityElectricity ¢ per kWh

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.

Cooling hours full-load hours per yearHeating hours full-load hours per year

2. The heat pump Carrier 37MAHAQ18AA3

Find a model (fills in the ratings below)

SEER2 cooling efficiencyHSPF2 heating efficiencyCooling capacity BTU/hHeating capacity BTU/h

3. What it replaces

Current heatingFurnace efficiency (AFUE %)Gas price, $/thermCurrent coolingOld AC rating SEER2 (10 ≈ 15+ years old)

4. Price replace the example with your quote

Installed price, $Rebates and incentives, $ utility, state

Heat pump, per year: $450
Current system, per year: $909
You save per year: $459
Payback: 14.2 years
Net after 10 years: -$1,907

Cooling $278Heating $172Electricity used: 2,812 kWhSaved vs. a minimum-efficiency heat pump: $252

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 18,000 BTU models

Arcoaire D5CSHAH18AAK · cold climate21.5 SEER2 · 12.4 HSPF2
York YRACXJ18WHAA · cold climate21.5 SEER2 · 11.5 HSPF2
Lennox MLB018S4M-1P · cold climate21.7 SEER2 · 9.8 HSPF2
Blueridge BMY18HH22C · cold climate21.5 SEER2 · 11.3 HSPF2
ZERO ZMSB-18HV-USHHCR2-O · cold climate21.7 SEER2 · 10.8 HSPF2
Bosch BMS500-AAS018-1CSXHC · cold climate21.5 SEER2 · 11.3 HSPF2
Convectair 500004494 · cold climate21.7 SEER2 · 10.8 HSPF2
Breeze33 BZ33-HYP18OUT2-G2-P · cold climate21.5 SEER2 · 11.3 HSPF2

See all 465 18,000 BTU mini-splits, ranked

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