Guide: Installing Your Own MrCool DIY Ductless Mini Split Heat Pump

The Ultimate Guide to Installing the Mr. Cool Third-Generation DIY Ductless Mini-Split Heat Pump

When it comes to climate control solutions for your home, the Mr. Cool third-generation DIY ductless mini-split heat pump stands out as an exceptionally versatile and user-friendly choice. Known for its enhanced features and simplified installation process, this product brings reliable cooling and heating right to your fingertips. In this comprehensive guide, we delve into the installation process, breaking down each step into manageable stages. This guide aims to equip you with all the knowledge you need to install your new mini-split heat pump with minimal hassle.

Pre-Installation Preparation

Required Tools

To achieve a seamless installation, make sure you have the following tools on hand:

  • Stud Finder: Essential for locating the best spot for your mounting plate.
  • Drill: A power drill expedites the process of securing your hardware.
  • Level: Ensures your wall template and mounting plate are perfectly straight.
  • Three-and-a-Half Inch Hole Saw: Ideal for creating the necessary hole in your wall.
  • Adjustable Wrench: You’ll need this for securing various components.
  • Screwdriver: Handy for putting together and securing different parts.

Selecting the Ideal Location

The first step in your installation journey is to find the right spot in your living space for the mini-split unit. When selecting the location, consider the following factors:

  • The mini-split should be positioned in an area with optimal airflow.
  • Ensure that the chosen space allows easy access to both indoor and outdoor units for maintenance.
  • The location should be free from obstructions such as furniture, curtains, or walls.

Step-by-Step Installation Guide

Step 1: Wall Preparation

Using the Wall Template

Once you’ve identified the perfect spot for your mini-split, it’s time to use the included wall template. Here’s how:

  1. Measure and Mark: Place the wall template on the desired spot. This template will help you mark the wall for drilling.
  2. Check for Studs: Use the stud finder to locate any studs. This will give you a clear idea of the best place to install the mounting plate.
  3. Align the Template: With the help of your level, ensure that the wall template is perfectly straight.
  4. Mark Drilling Points: Use a screwdriver to mark the drilling points through the wall template. These will guide you when you start drilling.

Step 2: Installing the Mounting Plate

Securing the Mounting Plate

Once the drilling points are marked:

  1. Detach the Mounting Plate: Use a drill or screwdriver to detach the mounting plate from the template.
  2. Line Up and Secure: Line up the mounting plate with the markings you made. While securing the plate to the wall, place a level on top to make sure it doesn’t slip or become uneven.

Step 3: Creating the Wall Hole

Using the Hole Saw

Now that the mounting plate is securely attached:

  1. Drill the Hole: Use a three-and-a-half inch hole saw to drill through your wall. The mark you made next to the mounting plate will act as the center point for your hole saw.
  2. Insert the Wall Sleeve: Push the provided wall sleeve through the hole. Ensure that it’s as close to flush as possible with the exterior wall. If necessary, use a saw or knife to trim the wall sleeve to the correct length.

Step 4: Connecting the Indoor Air Handler

Running the Refrigerant Lines and Wiring

Next, it’s time to connect the indoor air handler:

  1. Feed the Lines: Push the refrigerant lines, drain hose, and communication wire through the wall sleeve.
  2. Mount the Air Handler: Connect the air handler to the wall bracket. The top of the air handler should hook onto the top of the wall bracket and then snap into place at the bottom.

Step 5: Setting Up the Outdoor Unit

Positioning and Preparing the Unit

Outside, you’ll need to prepare the line set and ensure it reaches the outdoor condenser unit:

  1. Uncoiling the Lines: Uncoil just enough of the line set to connect the air handler to the condenser.
  2. Connection: Unscrew the color-coded caps on the ends of your refrigerant lines. Thread them together by hand, and then use two wrenches to secure them tightly.

Step 6: Finalizing Connections

Securing and Checking for Leaks

Once all the main components are in place:

  1. Open the Valves: Remove the valve covers on the condenser and use the provided Allen wrench to open the valves by turning counterclockwise until it stops. Be cautious to avoid over-tightening.
  2. Check for Leaks: Apply soapy water to the refrigerant connections at both the condenser and the air handler. Look for bubbles, which would indicate a leak.
  3. Seal and Cover: Once you’re sure there are no leaks, replace the valve covers. Wrap the refrigerant connections near the air handler with sound-deadening pads, then wrap them with the included vinyl tape.

Step 7: Electrical Wiring

Secure and Conceal

For a clean, professional look:

  1. Wiring Voltage: Ensure you note the voltage requirements for your particular system.
  2. Conceal Lines: Use the Mr. Cool line guard to cover the refrigerant lines, condensate hose, and communication wire.

Step 8: Testing and Final Checks

Initial Startup and App Setup

Once the installation is complete:

  1. Install Filters: Don’t forget to insert the included air filters inside the indoor air handler.
  2. Smart Controller: Insert the Mr. Cool smart controller for enhanced functionality.
  3. Testing: Power on the unit to ensure it starts without issues.
  4. App Setup: Set up the Mr. Cool Smart HVAC app for remote control and monitoring.

Advantages of Mr. Cool Third-Generation DIY Ductless Mini-Split Heat Pump

Ease of Installation

One of the standout features of the Mr. Cool third-generation DIY ductless mini-split heat pump is its user-friendly installation process. Unlike traditional HVAC systems, which often require professional installation, this mini-split can be set up by practically anyone with basic DIY skills and the required tools.

Energy Efficiency

The system offers exceptional energy efficiency, making it a sustainable and cost-effective choice for homeowners. It’s designed to operate efficiently, reducing your energy bills while maintaining optimum comfort.

Smart Features

The included Mr. Cool Smart HVAC app enables you to control your mini-split from your smartphone or tablet. This feature offers unparalleled convenience, allowing you to adjust settings, monitor performance, and even receive alerts if there’s an issue with your system.


Suitable for a variety of spaces, the Mr. Cool mini-split can be used in bedrooms, living rooms, garages, and even small commercial spaces. Its flexibility makes it an excellent solution for both heating and cooling needs.

Quiet Operation

Unlike conventional HVAC systems, the Mr. Cool mini-split operates quietly, ensuring a peaceful environment whether you’re working, relaxing, or sleeping.

Customizable Airflow

The mini-split offers customizable airflow options, allowing you to direct air precisely where you need it. This feature is particularly useful in rooms with uneven heating or cooling requirements.

Reliable Performance

Built to last, the Mr. Cool third-generation unit delivers reliable performance year-round. Its robust construction and advanced features ensure that you get the most out of your investment.

Safety Tips

Handling Tools

Always use hand and power tools carefully. When using a drill or hole saw, wear safety goggles and gloves to protect yourself from debris.

Electrical Safety

Ensure you turn off the power supply before you start wiring the unit. Make sure all electrical connections are secure and double-check voltage ratings to avoid any mishaps.

Refrigerant Line Care

Handle refrigerant lines carefully to avoid kinks or bends, which could impede the system’s performance. Always check for leaks to ensure your system operates efficiently.

Troubleshooting Common Issues

Unit Not Powering On

Ensure that all electrical connections are secure and that the circuit breaker is functioning correctly. Double-check the smart controller installation and app configuration settings.

Uneven Heating or Cooling

Verify that the air filters are clean and properly installed. Make sure there are no obstructions blocking the intake or exhaust of air. Consider adjusting the airflow settings to better distribute air throughout the room.

Unusual Noises

If you notice any unusual noises, shut off the unit and double-check all connections. Loose parts or unsecured components can be the cause of such noises.


The Mr. Cool third-generation DIY ductless mini-split heat pump offers an innovative and highly efficient way to control the climate in your home. Its DIY-friendly installation process, coupled with its advanced features, makes it an excellent choice for modern homes. Whether you’re a seasoned DIY enthusiast or new to home improvement projects, this guide provides all the necessary steps to ensure a successful installation.

So why wait? Take control of your home’s climate today with the Mr. Cool third-generation DIY ductless mini-split heat pump. For more information on these units or any accessories that come with them, visit

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