I have been using Comfortmaster, Inc. for about four years now. I am very satisfied with them, and I think they do great work. They have done many projects for me over the years including work on my air conditioning unit, furnace, and water heater. Most recently, they came out and deep cleaned the outside air conditioning unit and performed their yearly maintenance. I have a maintenance contract with them, and they are very good about coming out when they are supposed to service the units.