1. Don't use a contractor who wants to size solely on the Square foot of your home. The practice should be to size your needs according to the guidelines of Air Conditioning Contractors of America's Manual J. This is called a heat gain calculation. This is the proper and most accurate way of sizing air conditioning equipment to achieve the most comfort, and lowest operation costs. A unit too large will cost more up front, increase operation cost (The cost of operation will be increased by the unit short cycling. This is when the unit starts and runs for short periods of time then shuts off again. This is caused by the unit cooling down the house too rapidly and satisfying the the thermostat on temperature but not removing enough humidity or latent heat. This will increase maintenance costs and shorten the life of the equipment. The electric needed to start motors and compressor is 2-3 times the electric required to run them ) and have a shorter life then a properly sized unit. When buying air conditioning Bigger is not Better! (Oversized air conditioners run up the electric bill. The long run cycles operate cheaper then shot cycles. Oversized air conditioning equipment can cover up other problems such as leaky ducts, improper refrigerant charge, dirty filters and coils which may lead to costly repairs later. Over sized air conditioners cost more to buy and don't last as long. Oversized equipment makes your house clammy. Too large a unit cannot remove the humidity properly but will cool the air. The house feels cool when first entered but when moving around you can feel the humidity. Oversized unit move more air and could be noisier then expected. )

2. Don't be tempted by the lowest bidder. Ask the contractor for references from satisfied customers. Be willing to pay for the time to have the central air conditioning installed properly . Don't have the job sized properly and lose all the efficiency in a poor installation.

3. Check for duct leaks and crushed ductwork. All air leaks should be sealed with a good quality duct sealant (not duct tape).

4. Buy a high efficiency air conditioning unit. The minimum manufactures can produce is 10 SEER (This stands for Seasonal Energy Efficiency Rating. This is how air conditioning units are rated so all manufacturers are rated the same. The equal rating on heating equipment would be the AFUE rating. ). The higher the SEER number the more efficient the operation will be. Most manufacturers will offer a better warranty with the higher SEER models.

5. If you are replacing an existing unit it must all be replaced. Do not try to match up a new outdoor unit with old indoor unit or vice versa. The higher SEER new unit, will have reduced efficiency, and may encounter operational problems id added to older equipment.

6. Install for ease of maintenance. Make sure there is access to clean the indoor coil. The air filter must be serviced periodically, so it must be able to be removed easily for inspection and/or cleaning, or replacement.

7. Place the outdoor unit on the north or east side of the house if possible, out of direct sunlight. If the unit must be placed on the south or west side try to place it in as much shade as possible. Leave plenty of room for airflow on all sides, and at least 6 feet above (follow manufacturers instructions). Keep the area free of shrubbery and debris.

8. When mowing grass make sure not to discharge grass clippings into the outdoor unit.

9. When installing the outdoor unit allow good water drainage away from unit and do not allow the pad the unit sits on to touch the structure. If the pad is in contact with the building the vibration will carry to the indoors.