A split AC usually does not require additional evaporator coils, as the unit is divided into two parts. The outside piece consists of the condenser and the compressor, while the inside unit contains the evaporator. Since the front part is the main supply duct of your house, additional coils will create more damage to the system than produce cold air. However, you could add evaporator coils at the termination point of the duct.
Here is a simple DIY air conditioner repair method on how you could add an additional evaporator coil:
Since installing additional evaporator coils requires you to open up your room walls, it is advised that you carefully analyze the plan of your house and see which ducts are best for alteration. A split AC has the same duct as that of your heating system, so you will be connecting the coils to the warm air supply system.
You might need to disconnect the pipe at a bend or valve and place the evaporator coil in its position. You may also need to cut down a section of the pipe to ensure proper fitting of the coil. Once you have the coil in place, screw it into position. Make sure you have all the wires outside of the coil.
To connect the coil to the main evaporator coil, you need enough wire to reach the main coil. Once done, you need to find the wire that gives power to the main coil, and the connection that controls the cool air. Once you find this, join the main power supply wire and the new evaporator coil wire so that both coils run from the same source.
After this, you need to give a test run to make sure all is well. Leave the system running for two hours so that you can be sure it is functioning properly. When satisfied, you can wrap some pipe tape around the coil edges and close up the wall.
Although, most people would call in an air conditioner repair service, it’s not needed always. A little effort on your side and some basic tools will help you to do it yourself and avoid costly AC repair.