SplitAtlas

MRCOOL / DIY 5th Generation

MRCOOL DIY 5th Gen 12k 115V Mini-Split

Certified capacity
12,000 BTU/h[1]
SEER2
23.5 SEER2[1]
Heating floor
-13 F[2]
Voltage
115 V[1]
Install path
DIY install

The MRCOOL DIY 12k is the system that made "install it yourself over a weekend" a mainstream option: a pre-charged 25 ft quick-connect line set needs no vacuum pump or gauges for a standard wall install, and its warranty carries no professional-install condition. It runs on a 115V circuit - the single biggest practical advantage for retrofits where adding a 230V line is the expensive part - and its published spec sheet is unusually complete.

1 zoneDIY installCurrent

Refrigerant generation

R-454B - current-generation refrigerant

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Error Codes
MRCOOL DIY 5th Gen 12k single-zone mini-split system with indoor wall unit, outdoor condenser, and line set

Image: HVACDirect

Data completeness: 90%
Last sourced
Aug 17, 2026

SplitAtlas score

8.8 / 10

Methodology
Cooling efficiencyAbove average

(23.5 SEER2) among 12k systems

Heating efficiencyAbove average

(10.2 HSPF2) among 12k systems

Cold-weather performanceAbove average

(-13 F heating floor) among 12k systems

NoiseTop quartile

(18 dBA indoor min / 54 dBA outdoor) among 12k systems

WarrantyBelow average

(5 yr parts / 7 yr compressor) across the catalogue

Installation accessibilityTop 10%

(DIY-marketed; 25 ft precharged; 25 ft included line set) across the catalogue

Documentation & partsTop 10%

(3 manuals; spec sheet; 50 error-code rows; parts channel) across the catalogue

Key ratings

Rated cooling

12,000BTU/h[1]

Rated heating

12,000BTU/h[1]

Best-fit use cases

Single rooms, additions, garages-turned-offices, and any retrofit where hiring out the install or adding a 230V circuit would dominate the project budget. Less compelling if you already have an installer and 230V available - the efficiency premium of pro-install units starts to pay back.

Where this system ranks

Buyer review snapshot

Install difficulty

DIY-friendly
  • Electrical: 115V; MCA 18 A; breaker/fuse 20 A.
  • Line set: Quick-connect line connections; precharged 25 ft; included 25 ft.

Alternatives

Availability and price context

  • Sold at Amazon. Open the listing for today's price and stock.
  • Last seen at HVACDirect on Jul 27, 2026: $2,359.00. Open the listing for today's price.

Source date

Model data sourced
Aug 17, 2026
Page reviewed
Jul 18, 2026
Source-backed records
4
Newest source retrieved
Aug 17, 2026

Warranty tiers

Base
5 yr parts / 7 yr compressor - standard coverage

The score uses Base. Additional published terms are shown for reference and not counted in the score.

Review methodology

Strengths

  • True DIY install path: factory pre-charged 25 ft line set with quick-connect fittings, so no vacuum pump or gauges.
  • 115V operation - fits many existing panels without a new 230V run.
  • Rated heating down to -13F.
  • 18 dB(A) minimum indoor fan level - one of the lowest published floors we track.
  • Strong documentation: submittal sheets and manuals are public and complete.

Weaknesses

  • Certified efficiency (SEER2 23.5 / HSPF2 10.2 Region 4) trails the premium 230V competition - the Senville AURA 12k certifies higher.
  • The famous "lifetime" compressor warranty tier requires enrollment in MRCOOL's paid program; the standard warranty is what most buyers actually get - read the terms before counting on it.
  • Quick-connect line sets trade serviceability for simplicity: line length options are fixed, and a kinked or damaged set is a bigger deal than field-flared copper.
  • Street price typically runs above equivalent pro-install imports - you are paying for the install path.

Climate suitability

Minimum heating ambient
-13 F[2]
Certified heating at 5F
not published
Rated heating at 17F
not published
Rated heating at 47F
not published

Specifications

Show
Manufacturer
MRCOOL
Brand
MRCOOL
Product line
DIY 5th Generation
Model number
DIY-12-HP-WMAH-115D25-O indoor / DIY-12-HP-C-115D25-O outdoor
Indoor unit model
DIY-12-HP-WMAH-115D25-O
Outdoor unit model
DIY-12-HP-C-115D25-O
Number of zones
1
Max indoor units
not published
Rated cooling capacity
12,000 BTU/h[1]
Rated heating capacity
12,000 BTU/h[1]
Voltage
115 V[1]
MCA
18 A[1]
Maximum fuse or breaker size
20 A[1]
Breaker needed
not published
SEER2
23.5 SEER2[1]
EER2
12.5 EER2[1]
HSPF2 (Region 4)
10.2 HSPF2[1]
HSPF2 (Region 5)
7.6 HSPF2[1]
COP
not published
COP at 47F
not published
COP at 5F
not published
Minimum outdoor heating temperature
-13 F[2]
Minimum outdoor cooling temperature
-13 F[2]
Maximum outdoor temperature
122 F[2]
Indoor noise range
43.0/39.5/33.5/24.0/18.0 dB(A)[1]
Outdoor noise rating
54 dBA[1]
Indoor weight
24.91 lb[2]
Outdoor weight
83.11 lb[2]
Refrigerant
R-454B[1]
Refrigerant charge
30.34 oz[1]
Manufacturer coverage
not published
Line-set size
1/4 in liquid / 3/8 in suction
Included line-set length
25 ft[1]
Maximum line-set length
not published
Max line set per indoor
not published
Maximum elevation difference
not published
Max height between indoor units
not published
Wi-Fi support
not published
Energy Star status
ENERGY STAR certified[2]
AHRI certification number
not published
Warranty
Base: 5 yr parts / 7 yr compressor (standard coverage). Score uses Base.. Standard 5-year parts plus 7-year compressor; Extended Limited Lifetime Replacement only via paid MRCOOL Care Kit enrollment with conditions. Retailer's 10-year compressor with registration claim not supported by submittal; registration programs may vary.
Install path
DIY install
Retail price
last seen at HVACDirect on Jul 27, 2026: $2,359.00
Available retailers
Amazon, HVACDirect
Manual links
MRCOOL DIY Series Single-Zone Mini-Split System Installation & Owner's Manual, MRCOOL R454B DIY-5 service manual, MRCOOL R454B DIY-5 submittal
Specification sheet
MRCOOL R454B DIY-5 submittal
Last sourced date
Aug 17, 2026

Retail purchase context

Some retailer links may earn us a commission at no extra cost; paid relationships never change scores or recommendations. Affiliate disclosure

Paid link

Check price on Amazon
Check price at HVACDirect

Reference-only price

Last seen at HVACDirect on Jul 27, 2026: $2,359

Parts and filters

Fits MRCOOL DIY 5th Gen 12,000 BTU (115V). Part numbers and fit notes identify compatibility only; no manufacturer endorsement is implied.

filter-washable

Washable air filter

Fits
MRCOOL DIY 5th Gen 12,000 BTU (115V)
Filter care
Washable. Clean and reuse. MRCOOL does not publish a calendar cleaning interval for the primary filter. Replace if damaged or no longer cleanable.
Fit note
Fits DIY-12-HP-WMAH-115D25-O / DIY-12-HP-C-115D25-O. The indoor filter is a cleanable service item. MRCOOL does not publish an orderable model-specific filter SKU in the service manual; source replacements through the installer, place of purchase, or MRCOOL authorized parts support at https://support.mrcool.com/hc/en-us/articles/28733842948884-Where-Can-I-Purchase-Parts-for-MRCOOL-Systems.
Source
MRCOOL DIY 5th Gen Service Manual, 4.5 Error Diagnosis Without Error Code - Remote Maintenance, page p. 46 (Dirty air filter ... Clean or replace)

remote-control

Remote control

Fits
MRCOOL DIY 5th Gen 12,000 BTU (115V)
Fit note
Fits DIY-12-HP-WMAH-115D25-O / DIY-12-HP-C-115D25-O. MRCOOL does not publish an OEM part number for the remote; its authorized Mass HVAC store sells a 4th/5th Gen replacement.
Source
MRCOOL DIY 5th Gen Service Manual, 4.5 Remote Maintenance, page p. 46 (Replace the remote control)

smart-thermostat

MRCOOL Smart Wi-Fi Mini Stat

Fits
MRCOOL DIY 5th Gen 12,000 BTU (115V)
OEM part number
MST05
Fit note
Fits DIY-12-HP-WMAH-115D25-O / DIY-12-HP-C-115D25-O. MRCOOL publishes MST05 for its mini-splits. HVACDirect lists MST04, a different part, so no HVACDirect link is shown. MRCOOL's authorized store also offers the MTSK02 Mini-Stat.
Source
MRCOOL Mini-Stats, MRCOOL Mini Stats, page article (MST05)

quick-connect-line-set

25 ft Quick Connect precharged line set - 1/4 x 3/8

Fits
MRCOOL DIY 5th Gen 12,000 BTU (115V)
OEM part number
DIY25-1438-O
Fit note
Fits DIY-12-HP-WMAH-115D25-O / DIY-12-HP-C-115D25-O. Use this 1/4 x 3/8 R-454B Quick Connect line set for compatible 6k, 9k, and 12k MRCOOL DIY indoor heads. HVACDirect was verified as a live exact-part page on 2026-08-01.
Source
MRCOOL 5th Gen R-454B DIY Line Set 1/4 - 3/8, DIY 5th Gen 6k, 9k & 12k, page article (DIY25-1438-O)

Some retailer links may earn us a commission at no extra cost; paid relationships never change scores or recommendations. Affiliate disclosure

Paid link

Check price at HVACDirect

display-board

Display board (service part)

Fits
MRCOOL DIY 5th Gen 12,000 BTU (115V)
Fit note
Fits DIY-12-HP-WMAH-115D25-O / DIY-12-HP-C-115D25-O. The service manual identifies the display board as a replaceable diagnostic item, but does not publish a model-specific orderable SKU. Use model and serial through MRCOOL support or an authorized parts distributor.
Source
MRCOOL DIY 5th Gen Service Manual, 4.2 Error Display (Indoor Unit), page p. 36 (If the unit responds, the display board requires replacement.)

indoor-pcb

Indoor control board / PCB (service part)

Fits
MRCOOL DIY 5th Gen 12,000 BTU (115V)
Fit note
Fits DIY-12-HP-WMAH-115D25-O / DIY-12-HP-C-115D25-O. The service manual identifies the indoor PCB as the replacement path when the unit does not respond to the remote, but does not publish a model-specific orderable SKU. Use model and serial through MRCOOL support or an authorized parts distributor.
Source
MRCOOL DIY 5th Gen Service Manual, 4.2 Error Display (Indoor Unit), page p. 36 (If the unit does not respond to the remote, the indoor PCB requires replacement.)

louver-motor

Louver stepping motor (service part)

Fits
MRCOOL DIY 5th Gen 12,000 BTU (115V)
Fit note
Fits DIY-12-HP-WMAH-115D25-O / DIY-12-HP-C-115D25-O. The service manual calls for replacing the stepping motor when the horizontal louver will not move, but does not publish a model-specific orderable SKU. Use model and serial through MRCOOL support or an authorized parts distributor.
Source
MRCOOL DIY 5th Gen Service Manual, 4.5 Field Maintenance, page p. 50 (Replace the stepping motor)

air-cleaning-accessory

MRCOOL Cool Care kit (MMCK01)

Fits
MRCOOL DIY 5th Gen 12,000 BTU (115V)
OEM part number
MMCK01
Fit note
Fits DIY-12-HP-WMAH-115D25-O / DIY-12-HP-C-115D25-O. MRCOOL lists the Cool Care kit (MMCK01) for this model; each six-month kit includes a replacement air-freshening filter. This accessory is separate from the washable primary filter.
Source
MMCK01 COOL Care Program Kit, Compatibility, page article (Each shipment includes ... a fresh air filter. Compatibility: MRCOOL DIY Mini Split System.)
Find this model's filterReplacement Parts & Filters

Electrical requirements

Show
Voltage
115 V[1]
Voltage range
not published
Phase
1[1]
Frequency
60 Hz[1]
MCA
18 A[1]
Breaker needed
not published
Maximum breaker size
not published
Maximum fuse size
20 A[1]
Maximum cooling current
not published
Maximum heating current
not published
Manufacturer wire notes
not published

Installation considerations

Show
Liquid line
1/4 in[1]
Suction line
3/8 in[1]
Line connection type
Quick-connect line connections[3]
Precharged length
25 ft[1]
Included line-set length
25 ft[1]
Maximum line-set length
not published
Max line set per indoor
not published
Max height between indoor units
not published
Indoor dimensions
31.57 in W x 11.69 in H x 7.44 in D[2]
Outdoor dimensions
30.12 in W x 21.85 in H x 11.93 in D[2]
Indoor weight
24.91 lb[2]
Outdoor weight
83.11 lb[2]
Drain size
not published

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MRCOOL DIY vs Pioneer Quantum Ultra (12,000 BTU, 115V)

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MRCOOL DIY vs Senville AURA (12,000 BTU)

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Frequently asked questions

Can I install the MRCOOL DIY 5th Gen 12,000 BTU (115V) myself, or do I need a pro?
MRCOOL DIY 5th Gen 12,000 BTU (115V) is sold as a DIY-installable system with an included 25 ft line set, so a standard install needs no vacuum pump or gauges. EPA's Section 608 guidance says connecting pre-charged lines still requires technician certification. The electrical circuit is the part that is not DIY: plan on a licensed electrician for the dedicated circuit, and check whether your local permit office requires a permit for the install.
Will the MRCOOL DIY 5th Gen 12,000 BTU (115V) keep heating in a cold winter?
Rated heating operation extends down to -13 F. Certified heating efficiency is 10.2 HSPF2. Match that published heating floor against your climate's design temperature - below the low-ambient rating, output can fall off or the system can pause to protect itself.
What electrical circuit does the MRCOOL DIY 5th Gen 12,000 BTU (115V) need?
Published electrical requirements: 115 V voltage, 18 A minimum circuit ampacity, and 20 A maximum breaker or fuse sizing. Confirm the final circuit against the unit nameplate and local code with a licensed electrician.
What warranty does the MRCOOL DIY 5th Gen 12,000 BTU (115V) carry?
The manufacturer publishes these warranty tiers: Base: 5 yr parts / 7 yr compressor (standard coverage). Score uses Base.. Registration requirements and proof of qualified installation commonly affect coverage, so read the warranty terms before install day.

Data sources

Show
  1. MRCOOL: MRCOOL R454B DIY-5 submittalSourced - manufacturer technical document

    Covers Frequency, Maximum fuse size, Minimum circuit ampacity, Phase, Voltage, Included line-set length and more

  2. HVACDirect: HVACDirect product page DIY-12-HP-WM-115D25-OSourced - authorized distributor

    Covers Indoor dimensions, Indoor weight, Outdoor dimensions, Outdoor weight, Energy Star status, Minimum outdoor cooling temperature and more

  3. MRCOOL: MRCOOL DIY Series Single-Zone Mini-Split System Installation & Owner's ManualSourced - manufacturer technical document

    Covers Line connection type

  4. HVACDirect: HVACDirect product page DIY-12-HP-WM-115D25-OSourced - authorized distributor

    Covers Retail price

Last updated

Jul 18, 2026