If you are installing an AC system from scratch, your contractor should calculate the size of the cooling equipment you need by using recognized methods such as what you’ll find in the Residential Load Calculation Manual, aka Manual J, from the Air Conditioning Contractors of America (ACCA). If you already have ductwork for your heating, adding a central system can cost less.

Keep in mind that ducts used for heating might not be the right size or in the right location for optimal cooling. Your contractor should ensure that duct sections are properly sized and that there are enough supply registers to deliver sufficient air to the right spots. Undersized ductwork can make for inefficient and noisy operation. Here’s how to keep yours humming:



Keep it clean. Be sure hedges and plants are at least 2 feet away from the outside unit. Clean grills and filters monthly. Clear debris and dirt from condenser coils and check for blockages in the drainpipe.

Seal and insulate ducts. Air can escape through leaks or when ducts aren’t sealed and insulated properly, wasting 20 to 30 percent of the energy used to run your system. Sealing your ducts will keep you cooler in the summer and warmer in the winter. That’s why it’s called duct tape, not duck tape.

Seasonal checks. Once a year have a licensed professional change all filters, clean and flush the coils, drain the pan and drainage system, and vacuum the blower compartments. The contractor should also check to make sure that the system is properly charged with refrigerant, that there are no leaks, and that all mechanical components are working properly.