How to Install a Ductless Mini Split Air Conditioner

The MRCOOL DIY Ductless Mini-Split is perfect for cooling a room in the summer and heating a room in the winter. This video explains just how easy it is to install the ductless mini split unit in just a few hours.

When we bought our house, we didn't think to ask about heat and air distribution. If we had, we would have learned that our bedroom doubled as a sauna in the summer and a meat locker in the winter. Yay for multi-purpose rooms! Large fans and sleeping naked got us through the summer. Those nights were hot and steamy. (Not in a good way.)

We needed something quick and inexpensive. Thankfully we discovered the MRCOOL DIY Ductless Mini Split. I was sure we would have to have an HVAC technician come out to our house, which would cost thousands of dollars. But with a MRCOOL DIY Ductless Mini Split, I learned that it's just that! It truly is a Do-It-Yourself product.

The tools you'll need are a cross tip screwdriver, a drill with appropriate drill bits, a 3.5 inch hole saw, a stud finder, a spray bottle of soapy water, and pliers with an adjustable wrench or two fixed wrenches (19mm). You can find all of these supplies at your local hardware store.

Scope out your room to see where you'd like to mount your indoor unit. Keep in mind where you would like to keep your outdoor unit. It comes with about 25 feet of copper refrigerant line.

After you've used your wall template to see where you would like to place your indoor unit, it's important that you find studs that will line up with the mounting plate. I double-checked my studs and now I'm going to make marks on the wall template so I will know where I want to put screws. Make sure the template is level.

Before I drilled holes, I quadruple-checked and then placed the screws with my fingers. Make sure the mounting plate is level before tightening the screws. Then check again after the screws are secured.

Clearly, I'm not a handyman, because I'm not a man, but I'm not handy either, so I had to borrow tools from my mom. So, I'm just working with what I've got.

We drilled the 3.5 inch hole on the right side of the mounting plate, measuring about 4.5 inches from the center of the right side of the mounting plate. Drill at a slight downward angle for the drainage pipe.

Then, feed the bundled piping through the hole to the outside. It is important to be careful when feeding it through the wall because it is copper piping and you don't want it to kink. Then, hook the indoor unit on the mounting plate. It should click into place.

Then, connect the indoor unit to the outdoor unit. Remove the plates that cover the electrical wiring and the piping.

If you're not experienced with electrical work, it is recommended that you hire an electrician for this part of the installation. If you're confident, you can refer to the wire guide located on the cover plate on the inside of the unit.

Then, connect the refrigerant lines. Remove the caps. Thread the piping by hand, then use two wrenches to tighten the connection. Then, remove the valve covers. Use the provided Allen wrench to open the valves. Turn the wrench counter clockwise until it stops. Make sure you don't force it.

When all is connected, use soapy water to check for leaks.

That was a lot easier than I thought it was going to be. I know that if I can do it, you can too.

12 comments (view/add)
  • Dana
    Posted on 5/19/2020

    Have solid brick wall exterior garage. Outside ground to soffit is only 5 feet, inside garage walls are 8.25 feet high. Question is, can I bore the 3.5 inch hole to outside about 4.5 feet from the inside floor and yet still mount the inside unit at around 7.5 feet high? IE: does the exit hole have to be within a certain area right or left of unit as video shows, or can I put the hole anywhere below the unit and still run it outside to the condenser?
    Secondly, is the chiller/condenser unit ground/pad mounted only or can I mount it on the brick wall? Looking at the 18K 230V MRCool DIY unit.


  • Kyle
    Kyle from Ingrams
    Posted on 5/20/2020

    Typically, the exit hole is put right behind the unit, but there are knockouts on the sides that you can use to run the lines rather than going straight out the back. Run the lines out the side of the air handler and you can put the exit hole anywhere that you can reach with the lines. You can put the outside condenser on a wall mount. That's perfectly fine.

  • Ron
    Posted on 1/15/2020

    do you have to charge the lines on the 12K before turning the system on?

  • Kyle
    Kyle from Ingrams
    Posted on 1/16/2020

    If you're asking about the MrCool DIY 12k, then you do not have to charge the lines. If you're asking about any other 12k mini-split, then you would have to charge the lines.

  • Sean Corcoran
    Sean Corcoran
    Posted on 5/17/2019

    About the electrical connections. Does this require more than a 20 amp circuit? You don't address where the power is coming from or what the specs are.

  • Kyle
    Kyle from Ingrams
    Posted on 5/17/2019

    That's actually a manufacturer video. Whether or not you need a 20 amp circuit depends on the MRCOOL DIY model in question. For example, the MRCOOL DIY 24k is a 25 amp unit. The interior air handler gets its power from the outside condenser via a communicating wire. The condenser in turn must be wired to an appropriate disconnect box.

  • steve
    Posted on 5/1/2019

    I don't see anything showing you how to install the condenser?

  • Kyle
    Kyle from Ingrams
    Posted on 5/3/2019

    Condenser installation is shown after the 5 minute mark.

  • Donald
    Posted on 6/27/2018

    What do you do with the excess line set? What if you need to place the indoor unit farther than the 25 feet line? Do they come with extensions or longer sets? Do these units come with an option to add multiple heads? Need to provide service to 3 rooms.

  • Kyle
    Kyle from Ingrams
    Posted on 6/28/2018

    For a MRCOOL DIY, you can coil any excess behind the outside condenser. If you need to place the indoor unit further than 25 feet from the outside condenser, we would recommend a conventional ductless mini-split. Extensions are unfortunately not available for the MRCOOL DIY model. In any case, if you're looking to cool multiple rooms using different heads, a ductless multi-zone unit like the MRCOOL Olympus would be a better option.

  • Casey
    Posted on 5/18/2018

    No vacuum pump?

  • Kyle
    Kyle from Ingrams
    Posted on 5/21/2018

    The MRCOOL DIY is a pre-charged and sealed system. No vacuum is required.

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