Ask for a certified HVAC technician. Keep in mind that not all states require certification.

Your contractor should be licensed, well trained, and experienced to provide quality installations.

Ask your contractor about his or her training, experience, and membership in contractor associations.

Ask if he is insured and bonded. Good contractors own and use refrigerant recovery equipment and are certified to handle refrigerant in cooling systems.

Ask for proof of certification if applicable to your state.

Contractors should know how to properly size your home heating and cooling system (e.g., determine whether you need a two-ton or three-ton cooling system).

Don’t use a contractor who wants to size your unit solely on the square footage of your house.

Contractors should calculate equipment size using computer software or professional guidelines such as the Air Conditioning Contractors of America’s “Manual J.” To gather necessary information,

the contractor should spend at least a half hour poking around your house, taking measurements, and asking questions. He or she needs to measure ceilings, floors, windows, and walls, and check insulation throughout the home. Systems that have been sized properly to fit your home provide better humidity control, cycle on and off less frequently, and cost less than oversized systems.

Insist on getting a copy of the load calculations (or computer printout). These can be useful for comparing bids.

Ask your contractor to inspect your ducts for leaks, incomplete connections, and compatibility with the rest of your system. Ideally, your contractor should use diagnostic equipment and fix leaks using a quality duct sealant (duct tape is not sufficient). He or she may also recommend changes to your duct system. Since as much as 30% of the efficiency of your system is a result of your duct work, overlooking duct improvements may compromise comfort and cost you money.

If your house or water heater uses combustion (i.e., it burns something like natural gas or fuel oil), you should have a house pressurization test performed to make certain there is no danger of “backdrafting.” Backdrafting is when the fumes from the combustion process are pulled back into the home, threatening the health and safety of occupants.

Your air conditioner or heat pump condenser should always match the indoor coil.

Your contractor should replace both coils at the same time for maximum efficiency.

Have your contractor select an install location that provides for ease of maintenance. Make sure the inside coil can be reached for cleaning. Depending on the model, the contractor may need to install an access panel.

The coil should be cleaned every two years.

The air filter should also be easy to remove and should be cleaned or changed whenever it is dirty. (This can be monthly during peak season.)

If possible, have the contractor place outside air conditioning units on the north or east side of the house, out of direct sunlight. Leave plenty of room for free air flow on all sides, and at least four feet at the top. Keep the area free of debris and shrubbery.

Always obtain a written contract or proposal before allowing your contractor to install a new system and be sure to ask about warranties.

Remember, the contractor who gives you the lowest bid may not be the best choice for you. Paying slightly more may get you better equipment and better service.

Carefully evaluate a contractor’s proposal to ensure you get the equipment and service that best meets your needs.

Most contractors offer maintenance agreements to keep your system run smoothly for years to come.

Also ask about the warranty length, what it covers and if there are extended labor warranties available.

Be sure to ask your HVAC contractor about ENERGY STAR®-Labeled Heating and Cooling Products!

Clean and adjust thermostat

Check voltage and amp draw

Lubricate motors

Check air filters

Check fan-limit switch

Check electrical wiring and connections

Check temperature rise across heat exchanger

Check firing rate

Check gas manifold pressure (gas only)

Check for leaks Change nozzle (oil only)

Change filter (oil only).

Clean and adjust thermostat

Check voltage and amperage to all motors

Check air flow across the indoor cooling coil

Lubricate all moving parts (unless permanently sealed)

Check air filters

Check air flow across the outdoor coil

Check indoor fan relay

Check compressor contactor

Check electrical wiring and connections

Check that condensate drain is open

Check indoor coil Check operating pressures

Check temperature drop across indoor coil

Check indoor coil super-heat

Check outdoor sub-cooling

Check reversing valve (heat pump only)

Check defrost control (heat pump only)

Check outdoor coil

Follow the manufacturer’s maintenance instructions which generally include these instructions:

Keep air-supply outlets and return inlets clear of obstructions.

Clear leaves, brush, and dirt as they accumulate on the outside unit.

If there’s a pipe for draining condensate water, check it for blockage.

Check the air filter once a month during the operating season. Replace it if it looks dirty (some are washable).

Routinely have a professional contractor, such as our Service Pros, perform a pre-season check-up.

Consider purchasing a maintenance agreement, especially if it includes both cooling and heating systems. Most plans include two pre-seasonal check-ups and cost about $80 to $200. A plan may allow the contractor to spot problems before they lead to a breakdown. You also may receive priority service, which is handy when you are living in the sweltering heat. (See below for details of what the agreement should include)

Invest in a digital thermostat to program temperatures for your cooling system to follow throughout the day. For example, if no one is home during the day, a programmable thermostat can run the air conditioner or furnace at a temperature that will require less energy, then the program can adjust itself to a temperature to your liking one hour before you come home. Ask your contractor if a digital thermostat is right for you.

Invest in a 11-14 SEER model. 11-14 SEER are recommended for their combined performance in increased energy efficiency and product reliability.

Beware of replacing only one of the two main components if shopping for a replacement system. Replacing only the indoor or the outdoor unit of a system may result in a mismatch that compromises efficiency. Contractors also said these systems are more repair-prone than systems where the two units have been bought and installed together.

Think twice about buying a zoned system. Contractors said that zoned systems (which alter airflow to different zones in the house) require more cooling-equipment repairs than regular systems.

Look for an experienced contractor. One-fifth of the contractors surveyed said the primary reason for their service calls was improper application or incorrect installation.

Maintain your system properly. At least 40 percent of surveyed contractors said that service calls were primarily the result of improper maintenance.

The beauty of a central air conditioning system is that it can distribute cool air through the whole house as opposed to window units which are generally designed to cool a single room. Despite the larger initial cost, a central cooling system can still save you money by reducing your monthly utility bill. If new or modified ductwork is required, then your initial investment will rise. Central air conditioning units also vary in size and efficiency. A common, costly error is to install an oversized unit in your home.

Choosing the right unit for your home will largely depend on the contractor you choose because he will determine the capacity required. A good contractor will estimate the cooling loads and duct requirements by collecting detailed information in your home and using industry calculations to determine the correct size. (For more information on how to select a contractor, including what questions to ask him, see below on choosing the right contractor.)

There are different models, sizes and efficiencies available on the market. The type of unit, for example, a split system versus a single-packaged unit, may depend on the region of the country you live in and the type of home you live in (e.g., basement house, slab foundation, crawl space, etc). Regardless of the type of central air conditioner you install, the size and efficiency can have the most impact on your costs.

Air conditioner sizes, also referred to as cooling capacities, are measured in British thermal units per hour (Btuh). One ton is equal to 12,000 btuhs. A unit that has too little capacity may not keep the whole house cold, while an oversized unit will cost more and be more expensive to run.

A unit’s energy consumption is rated in SEER (seasonal energy-efficiency rating). The higher the SEER rating the less energy required to run the unit. The Department of Energy standards are currently a minimum of 10 SEER for central air conditioning units. The ratings can range from 10 to 18 SEER. Units with a 10 SEER rating are typically installed in new homes and as replacement models. According to a survey of over 500 contractors, a rating from 11 to 14 are mostly recommended because they are the least expensive to own overall and require the least repairs. While a 10 SEER unit initially costs less (maybe by a few hundred dollars) your monthly electric bill will be on the average $5 more compared to that of a 12 SEER unit. (Higher savings occur in the south, while northern regions may have little savings.) Additionally, some utility companies offer rebate programs to those with higher efficiency units installed.

The most expensive part of an air conditioner to replace is the compressor. Air conditioners typically feature a scroll or reciprocating compressor, depending on the unit size and efficiency. Check to see if the compressor has an additional warranty (e.g. 10 year compressor warranty), separate from the standard cooling system warranty.

Finally, if you are gone during long periods of the day (or night) invest in a programmable thermostat. With a programmable thermostat, your cooling system can use less energy while your gone and then adjust itself so the house temperature is comfortable when you arrive.

And if you are wondering whether you should turn off the air conditioner so you can open a window to enjoy a break in the warm weather, here is some advice: do not continually turn on and off your air conditioner to adjust to the changing warm weather patterns outside. If you want to open a window to get some fresh air, it is better to leave your air conditioner on rather than turning it off. If the inside of the house gets hot and you have to turn the air conditioner back on then your air conditioner has to work harder to cool down your house and everything in it.

2. The dealer should be affiliated with a nationally known manufacturer. The reason: many dealers take advantage of factory training to help you determine your comfort needs. As a result, when they make recommendations, you can be more assured they have selected the right system for your home. They are also trained in installation and service.

3. Contact individuals and ask if they were pleased with the dealer’s work.  Ask for references.  Former customers are an excellent source of information. Call these.

4. Expect an on-site evaluation visit. A good dealer should take a personal, thorough look at your home, evaluate your overall comfort needs and recommend the best system for you. Beware of a dealer that simply takes information over the phone.

5. Check local licenses. Depending on where you live, the dealer may have to comply with certain local or state regulations, so ask to see any applicable state and local licenses and insurance forms for liability and workmen’s compensation.

6. Don’t be afraid to ask questions. Ask for details about the firm’s experience, its long-term stability and the expertise of its staff.

7. Get a written proposal. To make a fair comparison, be sure the bids you are looking at include the services you’ve requested and are based on the same size and efficiency equipment and the same quality of workmanship. Be wary of a dealer who offers unrealistically low prices; it may mean corners are being cut in crucial areas.

8. Inquire about equipment and labor warranties. Warranties vary according to manufacturers. Make sure your dealer fully explains the terms of the factory warranty. In addition, many manufacturers offer optional extended warranties, which you may wish to investigate.

9. Ask you dealer about whether or not they offer preventive maintenance agreements. This is one of the best ways to ensure optimum efficiency and performance from your system.

10. Finally, insist on a written and signed agreement. Your home’s indoor comfort is important. Don’t gamble with it by selecting an air conditioning dealer by chance.