We had an air cleaner that my wife wasn't happy with since it was leaving a lot of dust. We have a service contract with One Hour Heating and Air Conditioning, so we called them up, and the guy came out and installed a new Heppa air filter into the unit. He knew exactly what he was doing, and was finished within a few hours. It was no trouble at all for him. We have been using the company for a while now and will continue to do so in the future.