diy 3rd gen

Introducing the MRCOOL DIY 3rd Gen E Star Mini-Split

  • January 31, 2020
  • By MR COOL

Maybe you’re the go-to fixer upper around your house, a home improvement guru, or just enjoy continuously reinventing your space. For any kind of DIYer, we have the product for you. Introducing the MRCOOL DIY 3rd Generation Energy Star Ductless Mini-Split Heat Pump.

The MRCOOL DIY 3rd Gen provides optimal comfort in a simple-to-install format. As you may have gathered, the 3rd Gen is the latest model from our popular DIY Series, and delivers even more flexible installation options than previous models. It requires no specialized tools, no special HVAC training, and no handling of expensive refrigerant.

And, as the name implies, the MRCOOL DIY 3rd Gen is Energy Star certified. This means you save money every month on your energy bill as your DIY unit maximizes its efficiency during both cooling and heating. This serious money-saving capability makes this product ideal for additions to homes already serviced by a high efficiency central system. Additionally, the DIY benefits older homes that need to be upgraded from outdated window air conditioners or low performance baseboard heaters.

Installation Supplies

So, what do you actually need to install a MRCOOL DIY 3rd Gen E Star heat pump?

You only need basic tools like a stud finder, drill, level, 3.5-inch hole saw, and wrenches. Our easy-to-read installation manual will guide you through the entire process, step by step. Should you ever get stuck or have a problem, you can call us at 270-366-0457 to speak with Tech Support.

Smart HVAC WiFi Controls

Simple and fast installation is great, but what’s so special about the DIY after that’s done?

One DIY feature our customers love is the Smart HVAC Controller®. This tech-savvy capability allows you to control your DIY unit with your smartphone. You control everything else in your life with your phone, so why not your air comfort too?

The Smart HVAC Controller for the MRCOOL DIY 3rd Gen E Star unit is packed with great features and capabilities. You can set and change your ideal settings with the touch button. No matter where you are in the world, you will be able to control your MRCOOL DIY simply and easily. Plus, you get even compatibility with Google Assistant.

Other Features

Other features include Low Ambient Cooling down to 5 degrees, Gold Fin corrosion resistance, auto-restart, Sleep Mode, louver position memory, Follow Me functionality, and more.

Low ambient cooling is ideal for spaces that require a set temperature 365 days out of the year. Trying to keep a server room or greenhouse cool on cold winter days? Low ambient cooling is what you need.

Gold Fin corrosion-resistant is even better. This protective condenser coating protects the coil against the corrosive effects of wind and weather. It helps ensure long term quality performance.

Auto-restart is a quality of life feature you will appreciate when you least expect it. Sudden power outages are annoying. Auto-restart means that your DIY mini-split will be back up and running in a matter of seconds when the power is out. That means if your power goes out in the middle of the night, you won’t have to move a muscle to get the air comfort flowing again.

Sleep mode is a great feature for setting when the household is quiet and sleeping at night. It helps you save money and sleep easier as your system runs efficiently to your ideal temperature setting.

Choose the louver position memory when you want your system to remember the exact settings you choose during the daytime. No need to reset your system with your choice in settings every morning. This function stores your favorite temperature, position and more so you can wake up without a worry.

The Follow Me function is designed to provide you with optimal comfort customized just for you. With previous heating and cooling technology, you would have to wait for the split system to heat or cool the entire room before you could regulate the temperature to your exact specifications.


Last but certainly not least, the MRCOOL DIY® 3rd Gene E Star Ductless Mini-Split Heat Pump comes standard with a 7-year compressor and 5-year parts warranty. That means you can rest assured you’re making a great investment in choosing a DIY for your next HVAC system.

241 thoughts on “Introducing the MRCOOL DIY 3rd Gen E Star Mini-Split”

  1. I am interested in this unit for a 900 sq. ft space. I have been searching your suppliers and I have had no luck locating either a 36,000 BTU, or 24,000 BTU. Can you help?

    Rod Russell

  2. I am looking for a unit to serve an added sunroom, approximately 200 sf. Do you have a system that would be suitable?

    1. For the DIY Series, the best fit would be the 12k model. Depending on climate conditions and other factors, the Advantage 9k might be a better choice for a 200 sq ft space.

  3. We would like to cool a 600 sq ft area with a 20 ft ceiling. What unit would you recommend?
    How noisy is the compressor? How many decibels of sound does it produce?

    1. For ceiling that high, a 36k would likely be the best fit. The indoor noise level is 54.5 decibels on high.

  4. I got a 3rd generation 1800 that we started yesterday.
    After a few hours my wife noticed a puddle of cold water.
    We pushed the drain out with the wrapped pipe package from the inside unit so I don’t understand why it should be doing that.
    Any suggestions?
    Certainly can’t be unmounted from the wall now that everything is hooked up.

    1. The MRCOOL DIY mini-split is specifically designed to make installation simpler and easier. For a conventional mini-split system, only the condenser is precharged. With the MRCOOL DIY, we precharge the condenser, the air handler, and the line set. Everything is 100% sealed and correctly charged from the factory. Basically, all you have to do is plug in the lines. They use special connectors that conventional mini-splits do not have that make the connection a no-brainer. Regular lines will typically require cutting, brazing, vacuuming, and charging.

  5. Can you tell me the recommended sq ft cooling area for the 12,000, 18,000, and 24,000 diy mini splits units?

  6. I have a shed that is 16×32 feet that I need to get control of the temperature to protect construction materials from freezing and overheating. Looking at 3rd gen systems. Need to to know power requirements, unit size, and price

    1. Depending on ceiling height, insulation, and climate, you would need either a DIY 12k or 18k. The 12k is a 120v 20 amp unit. The 18k is 240v 20 amp. Price can vary between dealers. The best resource for that is

    1. The 3rd Gen DIY is not pre-connected to the air handler. It also has a higher SEER rating and is Energy Star certified.

  7. I’m very interested in the 36k DIY unit you make. The efficiency and quiet specs are most attractive. But I need 30-35 feet of line. Are there any options for me?

    1. Yes! We have a line coupler coming out that will allow you to connect two different line sets together for additional length.

  8. I hear you are coming out with a multi-zone DIY setup, can you tell me when this will be available? I am ready to purchase asap just need to point me to where to buy???

  9. I live in Alaska and am interested in the DIY model to use for heating. At what outside temperature will it continue to efficiently heat? I’m looking to heat a 400 square foot room.

    1. The DIY will not function below 5 degrees. It will heat effectively near freezing, but loses efficiency as the temperature drops lower.

  10. I have two of the 24k units I’m using for a basement “green house”. I’m in Michigan so I get all four seasons and basically only need cooling to combat the lighting heat. Having two units the cooling is not a problem. My question is how can I maximize dehumidifying my area. There is a “dry” setting on the remote. But not very good information on how it works. I’d say ambient relative outdoor humidity is 60% on average. I’d like to keep my greenhouse as close as possible to 40%. Just curious how to maximize dehumidifying basically.

    1. Essentially, Dry mode runs the compressor at a low speed so as to lengthen the run-time. This increases the overall dehumidification.

  11. Hi! I’m in West Michigan and interested in a whole house mini- split system. Is there a DIY unit made for this scenario? 3500+ sf home including basement. Would I need 2 of the multi units? Thanks!

    1. There is going to be one very soon. This summer we will be rolling out our DIY multi-zone system. Given you are looking at cooling up to 3500+ sf, yes, you might need two of them.

  12. Hi, looking to purchase one of your units. Which split unit is recommended for garage 620 sq ft?


  13. Hi, I have a 400 square foot garage, I know 12k is the correct size, but can I get an 18k without compromising equipment?

    1. Hello – I have a new 1200 sq ft garage (24×50) – half w/ 14′ ceilings and half w/ 8′ ceilings. At the 8′ end, it is attached in an L shape to an older 400 sq ft garage. New garage is well insulated. Live in FL – would need a/c most of the time, heat occasionally. Would it be best to have separate splits or multi zone?

      1. You can get great performance from a multi-zone or multiple single-zones. A multi-zone would certainly be a neater option, since you only have to have one outside condenser instead of multiple. It should also be more cost effective.

  14. Hello,
    I am looking to install a gen 3 in my insulated 400 sqft garage in Michigan that I have converted to a home gym. I would prefer to only heat the area to about 50 degrees during the winter to reduce the cost to my electrical bill. I believe the lowest set point on most units is 62 degrees. Can I achieve a 50 degree set point with a wifi thermostat and would this cause damage to the unit?
    Thank you

  15. We are renovating an old farm and farmhouse and doing the majority of the work ourselves. (See We are looking at something for the 1,200 square foot house (2 bedrooms & a great room). We are researching pros and cons of this vs a traditional HVAC ducted system. Which size system will work for us, or should we wait for the multi-room? When will that one be available? And where can I buy it? It doesn’t look there’s a vendor around me (near Springfield, MO).

    1. Older buildings were never designed to accommodate bulky central heating and air conditioning air ducts. Which is why many historic home owners are turning to ductless mini-splits. A triple-zone ductless mini-split of around 36k BTUs sounds about right for a space that size. We hope to have the multi-zone DIY available in late May/early June. You can buy it online at Amazon, Home Depot, Lowe’s, IWAE, and other retailers.

  16. Have you run tests to know what % efficiency this will heat at in various ambient temperatures? For instance, is it 100% heating efficiency at 10hspf at 47 degrees F? Does it go down to 60% efficiency at 23 degrees F? Curious if you can share more on that in order to help me, a new proud owner to know how long to use it to heat in the shoulder seasons. Thanks!

    1. Taking the DIY 24k 3rd Gen as an example, it is AHRI rated (AHRI #204711124) to produce 100% of BTUs at 47 degrees. At 17 degrees, it will produce 14.8k BTUs. So while performance has taken a hit that is still a significant amount of BTUs for an air-source heat pump at such a low temperature. Efficiency degradation is more rapid as the temperature continues to drop. The unit will be in constant defrost mode around 5 degrees.

      1. Thank you for answering this question. I am still somewhat unclear about the efficiency of this particular unit that I have just installed myself. I understand that This unit produces 60% of the maximum heat output at 17 F, but I don’t understand the energy usage at that temperature. If a heat pump can have a 300% efficiency under ideal conditions, what is the actual energy usage efficiency at 17 F? Electric radiant heaters are 100% efficient so it doesn’t make sense to me that my heat pump is 100% at 47 F and only 60% at 17F. Can you please clarify this for me? I have other heat sources that I can use when it becomes more expensive to use the heat pump so it would be very helpful to understand where those efficiencies and costs intersect. Thank you.

        1. It might be easier to think about it in terms of percentages of the specific product BTUs. For example, if you have a 10k BTU mini-split that operates at 100% efficiency at 47F, then that means it is generating 10k BTUs worth of heat (or thereabouts). When you know how many BTUs you need for a specific area, then you know whether or not the output at a given temperature would be sufficient. Is that useful?

  17. I want to confirm the size needed for a single bay of a garage, so about 210 sq ft. I live in north Texas so it gets hot in the summer. I’m thinking the 12k DIY would be fine for that space. What do you recommend?

  18. I am installing the gen 3 DIY 12000 BTU in a converted charter bus. I don’t want to go out the side of my bus. Is there an option that it can come straight down out of the air handler. And I can go through the floor?

    1. You cannot go straight out of the bottom of the air handler. However, you can go out the side of the air handler.

  19. How is it powered? Do I have to wire it into my current network of wiring? Or is it as simple as plugging it in?

    1. Currently, the DIY 3rd Gen includes a 25′ line. However, we may modify that design in the future which would allow you to customize your line length.

  20. Do you all make a 18000 btu that is 110 volt or does it just comes in 230 voltage please let me know thanks

  21. I am looking at the advantage 18,000 unit. I noticed some model numbers are A-18-HP-C-230B and some are A-18-HP-230B. What does the “C” mean. the two units look identical.

    1. Sure, the “C” stands for Condenser, so with A-18-HP-C-230 it should just only be your outdoor unit. Where A-18-HP-230B would be your complete setup, Air Handler and Condenser. Also, if you see A-18-HP-WMAH-230 the “WMAH” in this will stand for your wall mounted air handler.

      1. So, do you have a mini-split system that will work in climate zones 5 through 8? I live in New England, where we have temperatures that reach below zero.

    1. Most 3rd Gen units are Energy Star certified and higher efficiency overall. Also, the Quick Connect lines are not pre-attached to the air handler.

  22. You stated above that you may modify the 25′ line design in the near future which would allow customized line length. I would like to order a unit but will wait for this option to be available. Please let me know when I can order with this option.

    1. A 16′ line is now available. Also, coupler kits are available that will allow you to extend line length.

  23. I live in Colorado at 8000’. Many times during the winter it will get below 5*F. Would it be effective if you build a green house around the unit ? Any other thoughts to make it work in the colder climates?

    1. Yes! The DIY is intended for do-it-yourself installation. It is completely pre-charged with special line sets. The Advantage is not. The Advantage is a conventional ductless mini-split.

  24. We cannot seem to find Mr Cool 3rd Generation Energy Star 36,000 BTU DIY for our enclosed pole barn 24×36 with 14 ft ceiling. It has sprayed foam insulation in ceiling and walls, no windows, 1 entry door, 1 garage door. We are in Florida and Don’t think 24,000 btu would be big enough. We installed 18,000 last year in our Sunroom and love it. So we need DIY. Thanks for any help.

        1. We had very high sales for the DIY 36k this summer. Most dealers are sold out. However, we are working to get the model back in stock as soon as possible.

  25. Can the pipes from the air handler be routed through the right side of the unit instead of the back? We bought the E Star 24K unit.

  26. We recently purchased a 12k DIY mr cool mini split and I’m curious about what happens with the heat when outside temps reach below 20 degrees. I noticed some literature saying that it “stops working”. Does that mean that the unit will completely shut off due to the outside unit becoming too cold? Or will it still work, just not as efficiently? We have a wood stove to help heat the area as well but it cannot heat the whole space on its own, so will that help the unit stay on below 20 degrees or does the inside temp have nothing to do with it at that point?

    Hoping this makes sense:)

    1. The DIY mini split will still work, but will lose heating efficiency at outdoor temperatures like 20 degrees and lower. It will not function at 5 degrees Fahrenheit or lower.

  27. Do you have any plans to make a DIY multi zone unit that is energy certified? It appears none of the DIY multi zone units qualify for the rebate in NH. New Hampshire’s rebate is $500 per ton. It’s cheaper for me to by individual units that do qualify but that does not seem to make sense.

    Thanks in advance.

  28. I see in your product literature that the 3rd gen DIY heat pumps will heat at 100% capacity to 5 degrees F and then less efficiently down to 23 below, but in a comment above it says the unit will stop functioning when the outside air is less than 5 degrees F. Can you clarify which is correct?

    Also, Is the air handler powered from the condenser (by the signal wires or other) or does it need to be powered separately?

    1. The DIY mini split heat pumps will not heat below 5 degrees Fahrenheit. Our Universal split system heat pump, which is a whole-home system that must be installed with supply and return ducting, can heat at 100% capacity at 5 degrees Fahrenheit and has a 78% heating capacity at -22 degrees. They are different products. For the DIY mini split, the air handler gets its power from the condenser, which must be hardwired.

  29. What size breaker is required for a 3rd gen 12,000 btu 22 seer minisplit? And is a none fused blade 20 amp disconnect outside ok for it?

    1. The 12k DIY needs a 20 amp breaker. While we do recommend going with a higher amp disconnect box, you can make a 20 amp disconnect box work for you if you would like.

    1. We apologize for this inconvenience, but we’ve had a high volume of orders recently and some products may be out of stock. We’re working our absolute hardest to get these units back in stock and to refill the stock of our retailers as well.

  30. Will you ever sell a 9k DIY model? My local HVAC technician is wanting to charge me $3,200 to install the non-DIY 9k Advantage model. Grrrrr.

  31. Do you guys have any plans on making longer pre charged line sets? For jobs that require a little more than 25 feet??

    1. We do not have plans for that. However, we do offer coupler kits that allow you to connect multiple pre-charged lines together for a longer reach.

  32. Do you have a low wall, or floor mounted option? I have an attic space that I am finishing the knee wall that the unit will be installed on is only 70” tall, the ceiling then slopes up to 8’.

  33. We have a GEN3 DIY 12,000 unit and love it! Is there capability to set it for “away from home“ to keep the 400 sf weekend cabin from freezing during the week while we are away? Likewise, to keep it from getting above 80° in the cabin in the summertime? Does the unit have to run 24/7 the entire time we’re away?

    1. You can set the unit on FP (Freeze Protection) Mode to maintain a minimal internal temperature. You could also control the unit while you’re away from the property with the SmartHVAC App.

  34. From what I’ve read here, the Mr Cool DIY runs at 100% heating capacity at 40°F and goes down to 60% at 17°F or 24°, i assume depending on which generation and BTU unit we are talking about. Since a heat pump delivers more heat, per unit of energy than than would be delivered through electrical resistance, and the efficiency of a heat pump goes down as the temperature drops. At what temperature does it make sense to turn off the heat pump and turn on the electric baseboard radiators.

    1. There’s no specific temperature point at which you should turn off a heat pump and turn on an electric heater. The rule of thumb is don’t turn on the electric furnace until you have to.

      1. MrCool DIY delivers 100% heating capacity 47 degrees F. At 17 degrees F Mr Cool heating capacity is drops to 60%. Am I correct in assuming that as the temperature drops closer to 5 degrees F, the heat produced is still cost effective as compared electric resistance, BTU/Watt?

        In your previous response you stated “There’s no specific temperature point at which you should turn off a heat pump and turn on an electric heater. The rule of thumb is don’t turn on the electric furnace until you have to.”

        Are you saying that the cost of heat the produced per watt is still less than electric resistance, even below 17 degrees F, but the output of the system could be lower than what is required to maintain desired temperature?
        Thank You

        1. Yes, that is basically what I’m saying. Electric resistance heat is the most expensive form available. Sometimes it may be necessary to use it, but don’t until you have to.

  35. I have a Mr. Cool It was installed in Oct. ran perfect then the outside unit got icy it was 26 and snowy now it again ran perfect now we have only cold air and its 40 outside , What can I do to correct this ????

    1. Did anyone from tech support get back to you on this? We’ve got the same issue going on but been trying for days and cannot get a call back or reach anyone. Let me know what fixed yours!

  36. What are the dimension of the gen 3 12000 btu unit that mounts inside the home? Making sure where I would like to place it will work.

    1. We have single-zone DIY mini-splits with one air handler, a DIY multi-zone condenser that can support up to three air handlers, and a DIY multi-zone condenser that can support up to four air handlers.

  37. I just ordered a DIY-24-HP-230B25 from Costco. Is this drop shipping from MrCool or Costco? It said 1 to 3 weeks… It’s for my 3 car garage (750 sqft) with 9ft ceilings in the hot desert of Phoenix AZ. 2×6″ construction home in 2007 flat santa fe roof (So no attick) or ceiling insulation – I just installed 7.5 seer foam with aluminum reflective siding against garage door panels… Is the 24K to much or be ok in these extreme summer dry conditions? I will not be running the A/C all day and night just 78 degrees when i’m working in the garage (Big sewing table – I’m in the RV awning business) I plan on turning it up to say 85-90 when not there and back down to 78 when i’m planning on being in the garage… Thank you for your expert input…

    1. That sounds like a space that the 24k should be able to handle. Shipping has been delayed due to the winter storm that disrupted logistics across the Eastern US.

  38. I’m looking for a DIY ductless unit that still can handle full capacity heating down to 5°F. I am looking to do a multi zone as well. Will the 3rd generation DIY work?

    1. While the single-zone DIY can heat down to 5 degrees Fahrenheit, it won’t work past that and it will not be full capacity at that temperature. The DIY multi-zone can heat down to -13 degrees, so it would have a better heating capacity at 5 degrees.

  39. I’m looking for a 3 zone mini split with heat for 3 bedrooms. I’m thinking a 18ooo btu main unit with 3 6000btu units 1 for each bed room is that available?

  40. I’m looking into getting your 18K unit for my open floor plan cottage. My issue is that 25 feet of line is about 15 feet too long. Do you have shorter lines?

    1. The electrical requirements for the DIY ductless mini-split vary with the size of the unit. The 12k is 110-115V, and the 18k, 24k, and 36k are 208-230V.

  41. I am an electrical engineer designing an off-grid home that will have an approximately 10 kW inverter system. Do you have available technical data on peak surge current and power vs. outside temperature for your 12 kBTU unit? I need this data to put into my design budget on the home’s electrical needs.

  42. I need to run the piping from the left side of the 12k gen 3 inside unit. The problem is that the inside unit piping goes all the way to the left exit. I don’t see a way to connect and be able to bend the piping through the hole without causing kinking. Any ideas ? Thanks.

  43. How do I order the 16′ line set? Pretty much all of the distributors/sellers only have units with 25′ line sets.

    1. Some retailers should have a sort of menu that you choose your preferred line set length from. If they do not, these retailers may be willing to take a custom order if you call them.

    1. Yes, but you must make sure that the BTUs of the air handlers you install at first add up to at least half of the BTU capacity of the condenser.

  44. I can not find any information about what is the heating capacity (maintain at certain percentage of output btu,i.e 70% at 5F) at 5F, -15F of the MRCOOL DIY 3rd Gen E Star Mini-Split system, thanks

  45. I installed a DIY-24-HP Heat Pump in Summer of 2020. Worked fine. We left for Winter in October. Left the unit on Freeze Protection. Worked fine until January. I was with the unit a couple days then and it was working but not making any heat. Now I am back and it won’t come on at all. What should I do? I believe it is still under warranty. Bought it through Lowe’s.

  46. Can the interior air handler be installed very low (almost ground level) near the floor instead of up high on the wall?

    1. We would not recommend that, as it would not receive the appropriate airflow and it could not blow air out to the best of its ability.

      1. Will you please clarify how not being pre-connected to the air handler changes installation options, and can I use a 3rd Gen DIY with a DIY multi-zone?

        1. The pre-connected air handlers could not accommodate different line set lengths, and the updated design can. As to compatibility between single zone and multi-zone, we would need to know specific product information before we could provide an answer.

  47. On a DIY E Series model 18-HP-230, I noticed that the short bundle of (2) refrigeration lines and (1) condensate drain tube that are bent down inside the air handling housing, that if they were not bent up in order to exit at right angles out the back wall, that they could conceivably exit out the left lower corner of the housing if the plastic housing was carefully cut. The 25’/16′ line set connections would have to be located inside the air handler also. However, this would allow for the line set and communication cable to exit out the left side , run exposed on the wall (inside a decorative raceway) before exiting the exterior wall out to the outdoor unit. Is this possible in the factories’ opinion and has this been done? I have a project that requires this and would like to consider a Mr. Cool unit for that application.

    1. Yes, that would be possible. A previous generation DIY, the 2nd Generation, featured a line set that was pre-connected to the air handler.

  48. The line set 16/25 I will assume that that is the length of the lines to the unit. Is this the only two options for the length of the lines. From the inside unit I have only 10′ to the outside unit, I will assume if there is excess I can roll the lines up.

    1. Yes, 16′ and 25′ are the only available lengths for a DIY ductless mini-split. Excess can be coiled loosely near the condenser.

  49. Any plans for a longer line sets? My shop is 36′ in length and I’d like to put a head at each end. 6 or 8 ft would work on one end and a 40′ line would work for the other. Any custom plug & play options? I’d be using the DIY Gen-3 34,400 BTU 16 SEER as my metal building but R-19 insulated shop is 28×36 with 12 ft walls and a 13.5 peak the length of shop. No Windows.

    1. We may come out with longer DIY lines in the future. However, the option available now is to use a coupler kit to connect two shorter DIY lines together for longer runs.

  50. Can we run line up through attic to an interior wall? We have purchased the extra line, but want to make sure we can run through an attic and down a foot to air unit?

    1. Yes, that is possible. Though if you do that with the condensate drain you would definitely need a condensate pump to compensate.

    1. The maximum fuse breaker for the 24k is 30 A. The minimum circuit ampacity is 18 A. It has a voltage of 208-230V. We recommend a 60A disconnect box.

    1. The maximum fuse breaker for the 24k is 30 A. The minimum circuit ampacity is 18 A. It has a voltage of 208-230V. We recommend a 60A disconnect box.

  51. Question: I noticed there are knock outs on the right hand side of the air handling unit. Is it possible to bend the lineset to exit there in an exposed manner, flush to the wall and drop down to the floor and run on the ceiling of the basement crawlspace to reach the compressor outside.

    1. That would likely be possible. Just remember to be extremely careful when bending the line set. You can also give us a call at 270-366-0457 so a technician can provide the best advice during your installation process.

      1. Thank you for the advice. I have been calling the tel number extension 702 but no one has replied as of yet.

  52. Hi,

    For a 12,000 btu Gen 3 DIY Mr. Cool, can I use 12/2 and a 20 amp breaker or is 12/3 or 10/3 with a 30 amp breaker recommended?

  53. I have found two different manuals on the DIY 27k. One recommends 10 awg and the other recommends 8 awg. The terminals on the compressor are too small to accept 8 awg. Will 10 awg be acceptable on this unit (6ft from main breaker panel) and what size breaker? This information is not provided anywhere on the unit.

  54. Good afternoon,

    Just purchased an 18k unit from Costco. When it arrived, the refrigerant piping cover was broken. Could I please purchase a new one from you guys, or please direct me to where I might find one? Thank you,

    Michael Wilson

  55. Hello, can you please confirm breaker size and wire AWG needed for the 24k BTU DIY unit? The online instruction indicates 30 MOP, and Pref. 12 gauge wire but would like to confirm.

    Thank you

      1. Can you please just double confirm that your 24k diy is good with 230 30a breaker and 12 awg wiring? You say that here and in your online manual but the 24k i just received says 10 awg. I already wired for the 12 awg based on online and above and would rather not now have to buy 10 and rerun the wires. thanks!

        1. I apologize, but for the 24k it is recommended to use #10 wire. National Wiring Guidelines recommend 10 gauge wire for 30 amp appliances like dryers, air conditioning, and the DIY 24k.

  56. Just started to install my MR Cool 3rd generation 12k unit. What do you recommend with the extra length of line set. I believe this unit has 25ft in the box. Where I am mounting everything I will only need 6-10 ft.

  57. Do you sell the DIY outside unit by itself? We purchased the indoor unit from a local liquidator store in our neighborhood and didn’t realize it’s not complete split ac system. It’s an mr cool diy e star series 12,000

  58. Placing the outside unit:

    We are using an 18k gen 3 for a newly finished attic. It’s a 2nd story to our home. Based on the length of the lineset that came with the unit (16ft) it won’t get us to the ground. And in order to wall mount it based on the back exterior of the home, we will need a couple 90’s and figure out how to get it to a position that makes sense. We unfortunately can’t come straight down out of the attic based on a small sunroom roof and steps to the basement. So ideally 19 feet gets us there so we are 3ft shy.

    The other option is to place it directly outside where we place the interior wall air handler. There is a small shed style roof there that we can access wall mount there possibly, but then it will only use a very small amount of line set and may have more direct contact with the elements (sun/rain, etc) and didn’t know if that is a problem….or what happens when we leave all the excess lineset rolled up? Is it my understanding you can cut the lineset on the non diy but you can’t on diy versions?

    1. We have wall mounting kits available that may close the distance. The line set must be used in order to ensure proper operation. The excess line set can be left coiled and placed near the condenser in a horizontal position without affecting the operation of the unit negatively.

  59. For two 18k heads heating and cooling, in Vermont, USA. Which condenser unit will most likely use least annual power. DIY-MULTI4-36HP230 or DIY-36-HP-C-230B?


    1. The second model number that you list is a single-zone 36k BTU DIY ductless mini-split condenser, so the only air handler that it is able to support is a single 36k air handler. The DIY-MULTI4-36HP230 is the only one out of those two capable of heating and cooling with two 18k air handlers.

  60. Do you offer, or intend to offer any of your evaporators (the interior unit) in black? The white is nice, but doesn’t match some households…

  61. What wire gauge and break is recommended for the DIY Gen-3 34,400 BTU 16 SEER Smart Ductless Mini Split Air Conditioner and Heat Pump.

  62. Kindly guide braker size,,fuse disconnect size and wire size for 18k btu DIY unit?
    20 amp breaker…30A fuse disconnect….wire size 12/2 awg is correct?

  63. DIY-18-HP-C-230B on the bottom of the outside unit I do not find a precut hole for the base pan drain I purchased this unit in Aug-2021 would that hole, have a knock out tab on it?

    1. I have the same issue! Whew, glad I am not wrong in my thinking – I’ve spent like 30-60 min trying to figure out if it’s one of those tabs etc. I checked /documentation for latest guide to see if it was updated, but directions are the same.

      Just called tech support and they are closed, but looking forward to a return call from them.

  64. I’m needing to know what size wire and breaker I’m needing 36k 4 unit 9k 9k 9k 18k..
    DIYM436HPW03B12.. it says a 45 amp breaker with a number six wire but a number six wire is rated for well over 45 amps

  65. I just purchased the 36k 4 zone (9k,9k,12k, 18k). My question is what size fuse and wire do I need to go from my main fuse box to the 60 amp disconnect? My main fuse box to the disconnect is 6 feet and the condenser is another 6 feet from the disconnect.

  66. Any plans to make ceiling cassettes for the DIY series? I assume that ceiling cassettes from your other product lines are not compatible with DIY? Thanks!

  67. Quick question. Sorry I know you get this alot.

    36K gen 3 DIY single zone. My electrician says 10 gauge wire, 60 amp disconect and 30 amp breaker at the panel. Total run is less then 10 feet. But your manual says 8 gauge wire. Which would be a 40 amp breaker.

    Will the smaller wire gauge and breaker be ok? Or does it need to be the 8 with a 40 amp breaker?

    1. Minimum AWG size is 10, so that should work, although the preferred AWG for a 36k multi-zone unit is 8. The max fuse breaker is 45 Amps.

  68. need 9000 BTU floor mount air handler four my 36000 DYI 4 unit multi compressor which came with 4 9000BTU wall units

  69. I have 2 small bedrooms (120sf each) & a small bathroom (60sf) = 300sf. Can I put together a 3 room duck system that connects a 12k 3rd gen. Unit to the 3 rooms? The rooms seem to small for a dedicated 12k unit.

    1. We don’t recommend attaching any ducting directly to the DIY’s or any other mini-split’s air handler. The doors to the bedroom and the bathroom could be left open, or venting could be put into the walls so that the air could reach the various spaces in your home.

  70. It’s my understanding that Mr Cool DIY and Perfect Aire DIYare built by the same manufacturer. Are there any significant differences between the two brands?

  71. I am installing a DIY-24-HP-C-230B. I purchased a 30A breaker, 10AGW wire (approximately a 30-foot run), and a non-fused 60A disconnect box. Will this be OK?

  72. Looking to buy a 2 zone 24k and 12k air handler Can’t seem to find one in stock. Are these still being sold in bundles?

    1. These are still available, we are just working on refilling our retailer’s stocks as quickly as we possibly can. We apologize for any inconvenience.

  73. Are the line sets the same from 3rd gen to 4th? Bought a new 4th but had an extra 3rd unused from a previously installed unit. I hooked up the 3rd gen line set and that one indoor unit and line is freezing over. I’ve cleaned and tested for leaks…

    1. As long as the fittings are the same, the line sets are fundamentally the same between generations. It is possible that the system is low in refrigerant. Please give us a call at 270-366-0457 as soon as you possibly can.

  74. I am installing the DIY-18-HP-C-230C 4th Gen single zone with ceiling cassette. MCA is 18 and MOP is 30. i plan on using 10/2 AWG and 30a breaker. is that correct?

  75. Great product! I am finally getting around to installing my 12k DIY unit on my 28′ race trailer. Outside condenser mounted on the tongue. What do you recommend for ease of install? Planning on coming up through the floor with lines, drain and electrical. Interior unit will be wall mounted as well as lines wall mounted. Right or Left line connection recommendations?

    Thank You!!!

    1. When looking at the front of the air handler, the line set should exit out of the right side. That would be the easiest installation method.

  76. Does gen 3 diy use an inverter? im also in dfw texas . i have a 24×30 metal building 10ft walls with a 12 ft peak. 1 8×10 rollup door 2 windows and 2″ of closed cell spray foam and am curious if an 18000 btu would work or better to have the 24000

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Are you a MRCOOL reseller or installer?
For questions about becoming a reseller or representative call 270-366-0457.

Sign Up