What are the most reputable hvac contractors?

Many states license contractors, including HVAC contractors. Check the consumer protection and state's attorney general for specific information about home contracting. The following website (http://www.nationalcontractors.com/hvac.htm) also provides contractor licensing requirements per state. If in doubt about a contractor, always ask for a list of references prior to any contracting, and inquire with the references to see if the contractor does quality work.