When do you need an HVAC service provider?
HVAC technicians do a variety of different tasks. They are usually called out when there is a problem with your heating and/or cooling system, but many companies also offer refrigeration services, so they can probably fix your refrigerator as well. Their services can be pretty expensive, so we would recommend that you do a little inspecting yourself before making the call. If you notice any problems check things like your thermostat settings and air filters to make sure everything is in proper working order.
How do you find a service provider?
There are literally thousands of HVAC service companies out there and most can be found in your local phone book. It is important to make sure that they are a licensed company and ask them to come out and give you a price quote for repairs before doing any work. If they take to long to respond or you just don't feel comfortable with their knowledge, look for a different company.