There are basically two types of HVAC guarantees. You get an equipment warranty provided by the manufacturer and a labor warranty provided by the contractor. Equipment warranties cover breakdowns or faults related to a defective part. If your refrigeration equipment is newer, it's likely covered by an air conditioning warranty from the manufacturer.
Most manufacturers offer limited warranties of 5 to 10 years for air conditioners, which typically cover the compressor. Some HVAC contractors also offer labor warranties for a certain period after the initial installation that cover defects associated with their work. If something goes wrong a few weeks or a few years later, a good HVAC warranty will help reduce your out-of-pocket repair costs and minimize your frustration during a heating or cooling crisis. The main thing to remember about HVAC warranties is that they cover the cost of replacing equipment, not the labor cost you would pay an HVAC company.
When you've just spent a lot of money on a new HVAC system, you don't want to spend more money on repairs during the first year after installation. If the parts don't work when the HVAC system has been properly maintained and used, the warranty will cover the repair or replacement of those parts. HVAC parts are generally guaranteed by the manufacturer that manufactured them for several years, and HVAC service companies or third-party insurers associated with them offer labor guarantees, when available.