When the time comes to repair, replace or add a central air conditioning and heating system to your home, take extra time and care in choosing a contractor. 

 It may be that you already have a preference for a specific manufacturer of heating and cooling equipment. The preference could be based on experience or the recommendation of family, friends or neighbors. 

 Tell the contractor of any problems you've experienced with your current system, such as hot or cold spots or maybe high humidity, so he can evaluate your needs. Also, look into a complete comfort system, including outdoor unit, indoor unit, air cleaner and thermostat. 

 Here are some tips for choosing the right contractor for your needs. 

1. Check credentials. Before making your choice, call the Better Business Bureau to make sure the contractor is reputable. Also, find out if they are a member of a local association such as the Air Conditioning Contractors Association. This, in itself, can be an indication of reliability.
2. Affiliation with a nationally known manufacturer. The reason is that contractors receive factory training to help you determine your specific comfort needs. As a result, when they make recommendations, you can be more assured they have selected the right system for your house. They also train in installation and service.
3. Ask for references. Former customers are an excellent source of information. Call these individuals and ask if they were pleased with the work performed.
4. On-site evaluation. A good contractor should take a personal, thorough look at your home, evaluate the overall comfort needs and recommend the system that best meets those needs. Beware of someone that simply takes information and then makes a recommendation on the phone.
5. Check all 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, insurance for liability and workmen's compensation.
6. Ask questions. Ask for details about the firm's experience, its long-term stability and expertise of its staff. This is especially true if you're adding air conditioning to an existing heating system where ductwork must be added. This case takes more planning and know-how to get the job done.
7. Inquire about warranties. Warranties vary according to manufacturer. Make sure the contractor explains the terms of your warranty and that you understand it. Many manufacturers also offer extended warranties, covering parts and labor which you may be wise to investigate.
8. Get a written estimate. To make a fair comparison, be sure the estimates you are looking at are for 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 contractor who offers unrealistically low prices; it may mean corners are being cut which will cause problems later.
9. Ask about maintenance contracts. Many contractors offer maintenance contracts that call for periodic maintenance of equipment. The fee for such contracts is usually well worth it in terms of obtaining optimum performance from your system. These checks are usually performed before the heating or cooling season begins.
10. Insist on a written contract. When you have worked out the details, ask your contractor to put it in writing. This will help you avoid any misunderstanding of what equipment and services were included.