DIY Mini Split Installation

In this DIY tutorial, I show you how I performed a DIY mini split installation for temperature and humidity control in my workshop.

Tools I Used



Download the Free DIY plans for this DIY mini split installation at the bottom of this post.


DIY Mini Split for Workshop and Home Office

My workshop is a separate building from my main house and it has 2 levels.  The first level is my workshop and the second level is my home office.  I decided it was best to remove the original HVAC system.  It was very old and not worth the cost of repair.

Home Office

I decided to install a DIY mini split in my home office during the fall of 2016.  After many hours of research of DIY min split installation articles, I installed the Mr Cool DIY 18,000 BTU 1.5 Ton Ductless Mini-Split Air Conditioner and Heat Pump (model:  DIY-18-HP-230A) for my home office.  I did not worry about cooling or heating my downstairs workshop because winter was near.  Additionally, I decided to test the performance of the ductless mini split in my home office before deciding on a cooling and heating system for my workshop.


I was pleasantly surprised with the performance of the DIY mini split in my home office and decided to purchase the same unit for my workshop.  I learned how to install a mini split during the first installation, so I decided to make a video and document my second mini split installation.


MRCOOL DIY Ductless Mini Split DIY-18-HP-230A

I chose the Mr Cool DIY ductless mini split (model DIY-18-HP-230A) because of the price, features, size, and it is 100% DIY.


MrCool DIY mini splits are DIY units as the name implies.

The refrigerant lines are pre-charged with R410A refrigerant, which eliminates the need for a professional installation.

The Mr Cool mini split install process is straightforward for an intermediate to advanced DIY’er – check out my video at the top of this post.  This DIY mini split installation was relatively straightforward and the instructions were well written.


The total price for the Mr Cool DIY Mini Split Installation was $1,457.00 plus $50.00 for the wall mount bracket.  The total price was $1457.00 before tax as of 2017.

I received multiple quotes from HVAC professionals on installing a similar unit to the Mr Cool DIY-18-HP-230A and the prices ranged from 2.5 to 3 times more than the Mr Cool DIY mini split.  

There are certainly many reasons and advantages to hiring an HVAC professional to install a mini split or conventional system.  However, this was my workshop and home office. 

Therefore, I decided it was worth the risk to buy the DIY mini split unit and install it myself.  If I were faced with the same decision for my home, I probably would have chosen to hire an HVAC professional.  

Ultimately, Reputable HVAC professionals guarantee their installation, support manufacturer warranties, and provide service agreements.

In addition, Mini Splits versus traditional central HVAC systems are beyond the scope of this article.  If you are faced with this decision, I encourage you research these topics and decide what is best for your situation and environment.

Mr Cool DIY Features

The features of the Mr Cool DIY mini split supported my needs even though it may not have the features of more expensive brands.  Below are the features I like most:

  • Dual heat pump and AC unit.
  • Refrigerant leakage detection system ensures the system operates efficiently without degradation due to corrosion.
  • WiFi adapter allows it to be connected to the Internet and controlled remotely via an app.
  • Warranty: 7 year compressor and 5 year parts.
  • Low Noise:  57dBA decimal rating.
  • Variable Speeds
  • Louver Position Memory and Swinging capability.


Mr Cool DIY Mini Split Size

Obviously, There are different Mr Cool DIY mini split size models for different size areas.  

Additionally, the Mr Cool DIY mini split model I purchased and installed covers 850 square feet.  

Ultimately, I was concerned with the 18′  high ceilings in my workshop, so I purchased this unit which covers more square feet than my workshop. 


How to Install a Ductless Mini Split Overview

Keep in mind, this DIY tutorial is not meant to replace the manufacturers instructions.

Rather, it is a supplemental to the manufacturers instructions.


Unboxing DIY Mini Split

First, I ordered the Mr Cool DIY mini split online and it arrived in 2 boxes:  the outside condenser unit and the inside unit.  

Ultimately, both boxes were packaged very well.  

Next, I inspected each part for damage very carefully.  I carefully inspected the refrigerant hose which was wrapped with a plastic coating and tie wraps.

DIY Mini Split Installation Unboxing


Assemble Wall Bracket

I purchased the wall mount for the outside condenser unit separate.  I chose the wall mount option rather than mounting the unit on a slab.  It is easier to assemble the wall mount bracket before installation rather than in the middle of the installation.

DIY Mini Split Installation Wall Bracket Assembly


Mount Inside Unit

I used the metal bracket and cardboard template to mount the inside unit.

DIY Mini Split Installation Inside Unit Bracket


Before proceeding, I attached the drain hose and checked for any links by running water through it.

I chose to mount the inside unit at the back wall of my workshop below the staircase.  

Under normal circumstances, the inside unit is mounted directly to a wall, but the back wall in my shop is not ideal for air flow.  

The back wall provided convenient access to the back of my workshop and the electrical junction box.  

So, I constructed a wooden support frame that matched the cardboard wall template and securely mounted it to the underside of the staircase.

DIY Mini Split Installation custom bracket


Next, I slowly bent the refrigerant lines to match the location where I planned to drill the exit hole – straight back.  The refrigerant lines can exit the unit to the right, left, or directly back (default is left).

DIY Mini Split Installation Refrigerant Pipes


Next, I examined the plastic latches.  The plastic latches were not broken or damaged.

DIY Mini Split Installation Inside Unit


I lifted the unit and set it on the metal bracket.

DIY Mini Split Installation of inside unit


Step 4:  Drill Hole & Route Refrigerant Bundle

I drilled the 3.5″ hole with a hole saw bit and 3/8″ arbor at a downward angle for proper drainage.

DIY Mini Split Installation drill 3.5 inch hole


Next, I installed the round plastic sleeve into the hole.

DIY Mini Split Installation Plastic pipe Sleeve


I fed the refrigerant piping through the hole.  I removed the protective passive wrap after the piping was through the wall.

Mini Split Route Refrigerant Pipes through hole


Next, I mounted 2 garage bike hooks to the bottom of the staircase so the pipe bundle could rest in them and keep them straight.  I put the drain hose through the hole below the refrigerant pipe bundle.

DIY Mini Split Drain hose through wall


There was a trim piece to the plastic pipe, but I didn’t use it.  I plan to build a box to hide the refrigerant pipe at a later date, so I decided to use spray foam to seal the hole.

DIY Mini Split Foam around Hole

Mount Outside Unit

The outside wall bracket for the condenser unit was easy to mount.  I made sure the cross support piece was level and secured it to the wall with screws.  Next, I slid the 2 support arms on the cross support piece.

Next, I slid the 2 support arms on the cross support piece.

How to Install a Mini Split - Outside Condenser Unit Arms


I heard a buzzing sound around my thigh while mounting the bracket.  I noticed a wasp nest about 6 inches away from my leg.  Thankfully, I didn’t get stung by one of them!

Mini Split Wasp Nest


The outside condenser unit weighs 80 pounds.  It’s not very heavy, but it is definitely awkward.  I placed the unit on the support arms and made sure the rubber feet and bolts were aligned correctly.  Next, I tightened them with a wrench and socket.

DIY Mini Split Installation Outside Condenser Unit


I used my magnetic I-beam level to make sure the top of the unit was perfectly level.

DIY Mini Split Installation Outside Condenser leveling


Connect Refrigerant Lines & Electrical

Next, I wrapped the excess refrigerant piping around the outside of the bracket in wide, loose loops.  I removed the top plastic cap to expose the electrical components and the bottom water tray to expose the refrigerant piping.

DIY Mini Split Installation refrigerant lines

DIY Mini Split Installation Electrical


After removing the plastic seals on top of the high and low side, I immediately attached the refrigerant piping.

DIY Mini Split Installation Rubber Cap Remove


I aligned the refrigerant pipes and made sure they were not stressed. After I tightened each screw connector by hand, I tightened the bottom screw connector and then the top according to the instructions.



The instructions are very specific, so I made sure to read them carefully. The couplings work with tapping rings, so they may leak if the pipes are loosened and reconnected.  I removed the cover on the top valve and opened the valve with a 19mm hex wrench counterclockwise. I repeated this process on the bottom valve.

DIY Mini Split Installation Loosen Hex cap


Next, I checked for leaks with a spray bottle that contained dawn soap and water.

DIY Mini Split Installation Check for leaks


Next, I connected the electrical cable from the inside unit to the outside unit. I made the electrical connections, attached the water box and electrical box, and put pipe installation around the refrigerant pipes.

I’m not including the electrical part of the installation process because I’m simply not qualified to provide this advice to you. I encourage you to call a professional electrician to perform this work because it is not worth the risk.


Install Remote Mount, Filters, & WiFi Adapter

Next, I installed the remote control cradle and the batteries.  I installed the remote control cradle near the door to my workshop.

DIY Mini Split Remote Install


I climbed up my ladder and installed the air filters.

Mini Split Install filters


The USB WiFi adapter was easy to install as well.  The port is located on the underside of the door.

How to Install a Mini Split WiFi Adapter


Setup WiFi and App

Once I connected to the SSID of the unit, I opened up the Mr. Cool app and configured the unit. The app doesn’t have the same features as the remote control, but it is still very useful.  I have 2 units and I chose the workshop unit.

DIY Mini Split Installation App home view


I can change modes from cool, to dry, to heat, to auto and back to cool by pressing the mode button.


I turned the unit off by hitting the power button to the lower left of your screen.

DIY Mini Split Installation Power Off

Power Off


I can set a schedule for the unit to turn on and off at a certain time. This works well, but I still login after it is supposed to shutoff because I’ve noticed that sometimes it doesn’t shut off.

DIY Mini Split Timer


Step 9:  Test Unit

There are specific instructions in the installation manual for testing the unit.  I used my IR thermometer to measure the cold air exiting the unit. This unit cooled my 25’x25’ workshop with 18’ ceilings quickly. I’m very happy with it.

Cool Air Measurement



In conclusion, I hope this DIY mini split installation tutorial of the Mr Cool DIY-18-HP-230A provided you with some value.

Checkout my other workshop projects such as how to repair THIS mini split (yes, I had an issue with it) and how to automate a dust collection system with voice commands.



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2019-04-13T22:13:56-05:007 Comments


  1. Chris K July 16, 2018 at 7:43 am - Reply

    I installed the 18K unit and had intermittent cooling issues that didn’t make sense because it wasn’t leaking refrigerant. I studied all the manuals and troubleshooting. I finally figured out that my problem was leaving the “FOLLOW ME” function engaged. It evidently sends messages to controller and if there’s a prolonged time of not sending the messages, the compressor shuts down. I guess it’s only to use and immediately turn off. Everything’s now working fine. You’d think there would be something in the user’s manual or troubleshooting about this.

    • Jeremy July 16, 2018 at 9:30 am - Reply

      Hi Chris,
      Thanks for your comment and very good info to watch out for. I agree that there would be a procedure to troubleshoot this issue.

  2. Luis Jimenez July 16, 2018 at 1:25 pm - Reply

    Milwaukee 49-56-0193 3-1/2-Inch Ice Hardened Hole Saw this tool can be use to drill on a concrete wall ? if you have any other suggestion or tool can be work on concrete let me know , thank you

    • Jeremy July 16, 2018 at 6:07 pm - Reply

      Hi Luis, a masonry hole saw bit large enough to fit the refrigerant pipes will do the trick if you need to drill through brick.

  3. Richard Allen July 30, 2018 at 1:00 pm - Reply

    Did you buy a Mr. Cool mounting bracket or a generic one? I like the one you used. Where can I get it? Thanks-Richard

    • Jeremy July 30, 2018 at 7:20 pm - Reply

      Hi Richard, here is the one I purchased.

      Thanks for visiting my site!

      • Toni hill April 18, 2019 at 10:59 am - Reply

        I am thinking about buying a used unit. Will I them have to refill the refridgerant?
        Is this a 220 electric unit?

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