Do it Yourself Central Air Conditioning Packages

Calculate the best-size system size and type for your home. A properly sized unit is essential for efficiency. A/C units are normally rated by British Thermal Units per hour or in tons. The calculations for unit size are based on the home’s square footage, its orientation, insulation quality and other factors. A contractor usually assists with these calculations, but you can also use special computer programs for making the decision.

Choose a location to set the condenser unit. A shady outside location that is away from windows is best. The condenser is the outdoor unit that releases hot interior air to the outside. Place it down on a condenser pad at least 1 foot away from the wall.

Find your furnace, which may be located in the basement, garage or utility closet. Place the evaporator coil inside the furnace’s plenum. This may require cutting a hole with metal shears and constructing a sheet metal shelf. The plenum is the source for your house's ducting. Cool air from the evaporator coil is distributed throughout the house through the plenum.

Cut a small hole in the exterior wall with a jigsaw next to the condenser unit. This is where your supply lines will run.

Attach the suction line to the appropriate condenser valve. Run the line through the house to reach the furnace. Do not attach it to the furnace, but cut it with plenty of extra length so it can be soldered by a contractor. Use a copper connecting unit to redirect the line at an angle if necessary. Avoid creating kinking this line.

Connect the liquid line to the condenser and run it through the house to the furnace, as you did with the suction line.

Set up low-voltage wiring between the main circuit and the compressor and evaporator units.

Install a thermostat according to the manufacturer's instructions, and connect it to the power main.

Contact a contractor to discharge the refrigerant into the system, solder your supply lines and check your work.