INTRODUCING: The NEW 4th Gen DIY Ductless Mini-Split

  • June 6, 2022
  • By MR COOL

Have you ever wanted to directly control how comfortable your home is, but you know that touching the thermostat equals high dollar signs? Now’s your chance to bask in full, complete comfort all throughout the year, because the DIY Ductless Mini-Split System is back and better than ever in its 4th Generation!

What’s New?

Everything that you’re used to with the 3rd Gen DIY is present in the 4th Gen, like impressive heating and cooling ranges, efficiency levels to get excited about, and a simplified do-it-yourself installation, but it’s all better. 

The 4th Gen DIY ductless mini-split has completely updated specs, ensuring extreme efficiency and compliance with new rules and regulations. The 12k has an impressive SEER of 22, making it Energy Star Certified, so you can install this system and enjoy lower bills for years to come. 

How could the DIY’s installation get any easier? It’s already just drill, mount, connect, isn’t it? Your electrician will be excited to work on this unit thanks to the addition of the new DIYPRO™ MC cable, which securely connects the air handler to the condenser. This cable provides protection against weather, pesky animals, even lawn mowers and weed eaters so you can keep enjoying refreshingly cool temperatures in the summer heat and toasty warmth in the winter chill no matter what.

That’s not all, though!

How Many Rooms Can It Heat and Cool?

The single-zone 4th Gen comes in four sizes: a 12k BTU system, which typically covers 500 square feet, an 18k BTU system, which handles 750 square feet, a 24k BTU system that heats and cools 1,000 square feet, and a 36k BTU unit that covers 1,500 square feet. 

These are perfect for more open areas, as there is only one place the air comes from with a single-zone unit. Sometimes one unit is all you need for complete comfort.

If you have a space that needs two units, but you don’t want to deal with two separate installations, we recommend the new dual-zone DIY! This 18k condenser can provide comfort to spaces such as two nearby bedrooms, a dual she-shed and man cave, or any twinning spaces that you can think of!

But what if you want to heat and cool your entire home? Previously, the multi-zone DIY could only support up to four zones, but we’ve added another condenser to the lineup to support 5 zones! In the right conditions, this 48k BTU is able to heat and cool a total of 2,400 square feet! This product will be available soon.

What About the Warranty?

We’re glad you asked, because this mini-split warranty is the best in the HVAC industry!

If you invest in us, we’ll invest in you. For the ultimate protection, you can sign up for a limited lifetime compressor warranty and a 7 year unit replacement warranty! This means that if your compressor breaks down, you’ll get a new one whenever you need, so the comfort never ends! 

The warranty lasts as long as you keep up your end of the bargain. To receive this warranty, you’ll need to sign up for the MRCOOL Care Kit program, to ensure that you’re taking care of your unit. Contained in this kit is a foaming cleaning spray, a bottle and a sprayer to rinse the unit, and a water collection bag with a drain tube to keep your house dry when you’re cleaning the system. Signing up for this warranty also entitles you to a standard 5 year parts warranty.

If you do not sign up for the MRCOOL Care Kit, you’ll still receive the standard 5 year parts and a 7 year compressor warranty. 

Where Can I Buy?

Improved efficiency, updated tech, and the warranty of a literal lifetime sounds pretty exciting right? To get your very own 4th Generation DIY® ductless mini-split system, visit one of our many retailers around the nation, or take a look at Let us transform your home with the power of the new 4th Gen DIY today!

54 thoughts on “INTRODUCING: The NEW 4th Gen DIY Ductless Mini-Split”

  1. I want someone to give me a call so I don’t have to be shopping on the phone for hours I don’t have time for that thanks !

        1. Yes, we use Shopify which offers a Shop Pay Payment plan. When you are looking at the product, it shows on the right hand side under the product with a “Learn More” so you can get more information on how the payment plan works. Go to this link on our website and you will see it right under the Price. Please feel free to contact us if you have further questions.

  2. I wish you would add a floor unit to your DYI solution. I have a mid-century modern ranch with large exterior windows, so a wall mount air handler on exterior walls isn’t gone to work. I have one guest room that is completely tongue and groove wood walls, so even if I did have access to exterior walls for a wall unit, I would never drill a hole in those wooden walls. Your ceiling cassette units might work, but my house has a skillion “lean to roof” roof with a very low angle, so space in attic is tight, and your cassettes are not DYI at the moment. I don’t know if it is possible, but if a floor unit can use the square vent hole for the current central air duct, after the duct is removed, then I would be down with that solution, as I have access via basement. I understand that the cassette could be seen as more of a professional install due to attic install, but I can’t see a floor unit being that much more difficult than a wall unit, especially if you have good access underneath via a basement. The crazy labor prices HVAC companies are now asking is just outrageous. They will quote you a small ducted split system for $11K, and a 3 zone mini split for $18K. If you want to make my house a install case study due to how unique it is layout wise, come on down. haha! Thank you for your time, and please release a DYI floor unit. 🙂

    1. We greatly appreciate customer feedback! Thank you for your message to us. Unfortunately, we currently do not have plans to add a floor unit to our DIY ductless mini-split series of products. Once again, thank you for your comment, and we apologize for any inconvenience.

    2. I would like to second this opinion. I also would prefer a floor unit, especially as I am concerned more with heating rather than cooling.

  3. I have a question. I currently have 2 of your units from a few years ago.
    I have a DIY-18-HP-230A and a DIY-12-HP-C-115AE.
    They cool very well. But once it falls to around 40 degrees or less the heat stops heating. I want to know if the 3rd or 4th generation will heat better?
    I want to be able to heat down to at 10 degrees at close to 100% efficiency.
    What is the heating range of the 3rd and 4th generation models?
    And at what temperature do both of those models drop from 100% efficiency?
    Going to be replacing these soon, and don’t know if it’s worth waiting for the 4th Gen.

    1. When it comes to the 3rd Gen, the 12k BTU unit can heat in temperatures as low as -13° Fahrenheit. The 18k, 24k, and 36k BTU units can heat in temperatures as low as -4° Fahrenheit. The 4th Gen 12k, 18k, and 24k can heat in temperatures as low as -13° Fahrenheit, and the 36k can heat in temps as low as 5° Fahrenheit. Performance spec information can be found on our Documentation page, at

  4. ASAP I need a 4th gen 9k + 9k +24K system with a 16ft+25ft+50ft install kit. Please price and send information for ordering system. I’m in the Wilmington Delaware area.

  5. Does the new 4th gen actually stop cooling when the setpoint is reached? My 3rd generation 12K DIY never stops and makes the room a meat locker until I manually turn it off. Mr. Cool support was nearly impossible to reach, and when I did, was not able to provide any solution.

  6. Does MRCOOL have a floor unit or can it be mounted lower on a wall. I want to replace an old wall mounted motel type ac with MRCOOL in the same location.

    1. The line set lengths are 16 feet and 25 feet. These line sets can be linked together using the appropriate Quick Connect coupler kit.

      1. Where can you purchase the 16 ft line set?

        We are interested in the 27k 3 unit split, however each outer unit will need to be approximately 25 feet from the center unit based on walls and windows, then will require an additional 8 feet from just below the roofline to the ground.

        It seems wasteful to get 2 extra 25ft sets just to reach the ground, but I can’t seem to find anything less than 25ft lengths.

        Thanks for your time

        1. You should be able to purchase it at any of our retailers. The correct model number for a 16 foot line set for this system would be DIY16-1412.

  7. Will you guys have a low wall handler for the 48k 5 Zone unit? I have been waiting for four months now for the 4gen and was told by folks to wait for this new release. I have a couple of space where the standard air handler can’t fit. Low wall mounth will be better. Can you folks please let me know. Thanks, Paul H

  8. We are building a new Hangar Home. Metal building with a 1500sq ft. home being built inside of it. Single level two bedrooms. Location is northeast Tx. Thinking I need a system with 4 units.
    Mark German.

  9. do you offer a 12k floor unit (not wall mounted)? Also, we currently have EZBreeze ‘windows’ installed in in 3 season room and they are definitely not as efficient as having double paned windows so not sure if installing a mini split system would be a waste of money due to the energy loss

    1. Unfortunately, we do not have a floor unit. We apologize for any inconvenience. It’s likely that a mini-split system would be more efficient than window units. Take a look at for more information on our DIY ductless mini-splits.

  10. I require a DIY18HP230B50. Your dealer map does not provide retailers in my area but I know Lowes or HD do sell units in my area. Can you provide a list or can Lowes or HD order this bundle for me.

  11. Do the 4th gen air handlers work with 3rd gen condensers? Not sure if the condensers are the same. I bought a multi 36k system when it was 3rd generation and had them ship out the condenser first and 18k Air handler as they were out of stock of the 9k and when they received the 9k air handlers they shipped out 2 4th gen 9k.

  12. Do all diy 4th gens have an inverter compressor? If yes, does the air handler and the compressor stay on constantly if the set point is reached?

    I want them to stay on constantly but just throttle back the compressor cooling power and power use (variable btu output). Can the diy 4th gen do this?

  13. My unit seems to keep running even after it reaches the temp I have the thermostat set on. How do I fix this?

  14. My application will require running the DIY line- sets through an interior wall which will mean that the 90 degree bend will need to be tighter as opposed to if it was run down an outside wall. Is there less of a concern with the fourth generation units as they’re designed with some more protection against kinking?

    1. You should be just as careful with the line set. The line set is not very different between generations. While you should be able to do what you intend, you will need to make the bend extremely carefully.

  15. My MrCool DIY 18k unit will not cool. The E1 has displayed and electric amps were checked so i assume the control panel is bad. It not communicating with each other. I would like a new one under the warranty contract. It was installed on 5/19/2022.
    This problem needs to be addressed ASAP. I purchased the units on Amazon on 4 /10/2022.
    Due to your poor support department I have had togo to the added expense of purchasing a window mount as we are in a heat wave!

    1. We apologize greatly for this. Would you mind sending me a reliable contact number so that someone from our service team can reach out? Your personal information will not be made public.

  16. So I just received my Mr Cool 18K mini split thru Costco. The air handler is a 4th Gen, while the condenser is a 3rd Gen. Why the difference, and is this the normal pairing?

  17. I have a 1700 sqft home. I currently have an old central ac that isn’t keeping up. The house has 3 bedrooms, a lower level and a big open area (living room, dining room, kitchen. How many units would I need? Also, do you have lines that stretch from one side of the house to the other? Thank you.

    1. Sizing would depend on the specific square footage of the spaces inside your house that you want to heat and cool. Our newest unit in the 4th Gen series, the 48k BTU 5 zone multi-zone DIY ductless mini-split, was recently released. You can find more information regarding sizing and pricing at

  18. Can you purchase a ceiling mount for the
    MrCool E Star DIY 4th Gen 12k BTU unit
    Rather then the wall mount.
    I saw your units at Costco.

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