Ductless AC Installation, A Homeowner's Guide...

Ductless ac installation can be a do it yourself project in some countries. (The U.S. and some other countries require a certification to handle refrigerant equipment if it contains R-22.) We will look at installing the basic unit with a high wall fan coil unit. The process is very simple and does not require many tools. The typical contracting company will charge several hundred dollars for this service but you can do it yourself and keep that money.


A load calculation should first be performed to ensure that you are installing the proper size of unit.

The first step in your ductless ac installation is to select the location for the fan coil and condensing unit. The fan coil should be placed in an area of the wall that will allow free air movement. For ease of installation the unit should be located on an exterior wall. The condensing unit should be located where the airflow will not be obstructed by buildings, shrubs, etc.

Next the bracket for holding the fan coil must be mounted on the wall. The top of the bracket should typically be at least four inches down from the ceiling for a high wall unit. Then, a three inch hole should be drilled through the wall to the outside. The easiest way to do this is with a hole saw. It is important that the bracket is installed perfectly level or tilting very slightly toward the drain outlet.

For many units the wiring harness does not come wired to either unit. Prior to placing the fan coil on the mounting bracket, you should connect the wires to the fan coil. The wire designations vary with the unit but a diagram is provided to tell you what wire goes to each terminal.

After the fan coil is wired, the unit can be placed on the mounting bracket. The wires, drain tube and refrigerant line connections should be taped together and pushed through the hole in the wall at the same time. The condensate drain line should be under the refrigerant pipes to ensure proper condensate flow.

The top of the fan coil unit can be hung on the hooks of the mounting bracket. Then the fan coil can be pulled down and it will snap into place on the bracket.

  Ductless AC Installation, The Outdoor Unit

On the outside, the refrigerant lines should be connected to the fan coil and the condensing unit. **HOT TIP** For proper operation and long equipment life, any excess piping should be cut off and the pipes re-flared before attaching. The connections should be very tight to avoid leaks of refrigerant.

Now, the wires can be connected to the condensing unit. Be sure to follow the wiring guide provided with the unit.

A leak check should be performed on the refrigerant lines. In some countries it is permissible to release a small amount of refrigerant from the condensing unit to do so. In the U.S.A. and some other countries, this is not allowed. In these countries it is necessary to use dry nitrogen. A simple way to find leaks is to use a heavy liquid soap and spray it on the connections. Watch for air bubbles which indicate a leak.

Next, the lines should be evacuated for moisture removal. This is accomplished with a vacuum pump. Then the refrigerant can be released from the condensing unit to the system. This is accomplished by opening the valves on the condensing unit.

Complete the ductless ac installation by attaching the hose to the drain outlet and in some cases wrapping the lines. The lines should be attached to the wall to secure them and prevent excess vibration which can cause refrigerant leaks.

You can complete your ductless ac installation by turning on the power and performing an operational test. The refrigerant levels should be checked and adjusted per the manufacturer's instructions.