When you are looking for a quality company for the services offered, you need to make sure that the Keller HVAC service is one of those quality companies. The air duct cleaning services should be professional in their business and should have years of experience in providing air duct cleaning services. The company should also be insured so that in case any unforeseen circumstances occur and they can't do the air duct cleaning, they have compensation coverage. There are several things that should be done when you are looking for a service such as the inspection, the quote, and the inspection follow-up.