My Mr. Cool Mini Spit Nightmare

FREE Soundproofing Workshop:

Over the past three years I have recommended the DIY Mr. Cool ductless mini split as a viable option for home studios. In this article I am going to explain why I no longer think this is a good option. 


1) Three Weeks of No Heat at 4 Degrees 

Every once in a while we learn from experience rather than books or videos. This is one of those situations. In theory the DIY Mr. Cool systems are great. They cost about $1200-$1500, you can install them yourself with a few tools, and they can heat and cool a room while staying somewhat quiet. You can always turn them off if they are too loud. Awesome, right? Well here is what happened to me so you can see where things go wrong. 

First, this past fall, three years after my mini split install the compressor stopped working. I think this was due to a a power surge hitting the unit and frying the logic board. The lesson here is to add a surge protector to your condenser. 

Through this experience I learned that most HVAC technicians have never heard of Mr. Cool and needed to call their tech support line. The tech could never get ahold of tech support. In fact, nothing happened until I emailed Mr. Cool and got involved. After several weeks of back and forth they finally decided to send me a new condenser outside unit free of cost except for the cost to ship it and hire someone to install it. 

This was great, minus the three to four weeks I didn’t have any heat in the studio because Mr. Cool’s tech support was not top notch. Then about two to three weeks after installing the new condenser I realized that the mini split was not putting out any hot air. 

I called another HVAC tech to come out and just yesterday he said that I had a refrigerant leak in the line set in my double wall system and that the only fix would be to open up the walls. 

Well, you can imagine that this is not an ideal scenario, so the lesson learned here is do not put your line set with the refrigerant lines where you cannot access them easily. It would have been best to run the line set on the outside of my studio so that we could easily check for leaks. 

This might lead you to wonder how a leak would open up? The HVAC tech said that a screw or nail could tag the line or the vibration of the line itself over time could rub against a sharp edge and open up. This could be what happened to me. We may never know. 

So here I am writing this in my studio with an oil based space heater (just to rub salt on the wound my internet is also out and Google Fiber can’t figure out what is wrong). What is the lesson for you in building your own soundproof home recording studio. 


2) Ducted Mini Splits Vs. Ductless Mini Splits

There are two types of mini splits and to be honest I am surprised at the the number of HVAC techs, contractors and even architects that don’t know this. The mini split I have is called a ductless mini split, meaning there is a condenser unit outside and a mini split wall or ceiling cassette unit on the inside. The condenser outside is connected with a refrigerant line set that runs to the head unit on the inside of your room. 

This system is great for most situations, but it is not great for soundproofing. First, the unit is quiet, but not that quiet. Now that it has not been working I am realizing how noisy it really was. In an ideal world you should not have any mechanical noises in your studio. This means no mini split head and only using solid state hard drives if possible.

The other superior option is to use a ducted mini split. This is a system where the mini split is not attached to the wall or ceiling, but is instead installed in the attic or a separate mechanical room. The mini split unit is an air handler and it pulls air from the room heats or cools it and then pushes it back in the room. Simple right? Well, for a normal room, yes, but for a soundproof room, well it is a different story. More on that install in a second. 

So why didn’t I install the ducted mini split in the first place? Great question and with 20/20 hind site I sure wish I had. The reason I installed the DIY Mr. Cool Ductless mini split is the same reason you would. It is cheaper and seemingly a great option if you have never built a recording studio before. Experience is everything and I am learning that the really really hard way. 


3) Overview of the Ducted Mini Split System


Short of finding a solution to my mini split problem that is an easy fix, I am really stuck between a rock and a hard place. I have to open up my walls and find the leak and repair it, but what if another leak happens? Option two is to run a new line set along the outside of the building and then punch a whole through my outside wall and connect the new line set to the existing mini split head. This is a cheaper solution, maybe, but it requires keeping my noisy mini split in the room and reducing my soundproofing by having a direct hole from the outside to the inside. 

This leads me to option three. Which, I think is the best option albeit maybe a little more expensive. I could buy the Olympus Mr. Cool 9000 BTU ducted mini split. I could install it in the ceiling of my bathroom attached to my studio. Then I could connect that mini split (hopefully) to my existing condenser outside unit. I could then tie in the mini split duct work with my ERV and baffle box system and have fresh hot and cold air supplied to my studio that is also quiet. Perfect right?

The downsides to this solution are what keep most DIY people from doing this set up. The reason? Cost! But, this saying is very very true in recording studio builds. You get what you paid for. I repeat because this is the greatest knowledge and wisdom I can give you. You get what you pay for. All of your problems down the line in your studio will come from taking the cheaper DIY approach. 

So, to install a ducted mini split you must hire an HVAC tech. This will cost you thousands of dollars because those guys really know how to charge what they are worth. Lastly, if you want my best advice. Don’t buy a cheap unit. Buy a Mistsubishi or Fujitsu ducted mini split. Size it correctly for your room and you will avoid so many issues. 



Learn from my mistakes. They continue to cost me time and lots of money. Saving money on the front end doesn’t mean you saved money if you spend thousands of dollars fixing your mistakes on the back end. 

Buy a Mitsubishi or Fujitsu ducted mini split. If you can’t afford those units ask your HVAC installer for the next best option. I would stay away from Mr. Cool. There tech support alone is good reason to avoid them, but their units are cheap for a reason. That reason is that they are not built well and are prone to breaking in my experience. 

If you do use a ductless mini split system, run the line set outside of your studio and do your best to seal up the hole you run through your wall to help keep the wall soundproof. Remember, the ductless mini split should be a last resort not your first option. 

I hope this article was helpful and I hope you don’t go through what I am going through. Learn from my mistakes and you will thank me three to five years down the road.