Our Elite® Series Oil Furnaces Provide Warmth and Reliability to Your Home Our team at Hix Air Conditioning Service, Inc. is available to answer your oil furnace replacement questions. We can even visit your house in the Muskogee County area to help you determine the best oil furnace for your needs. Call us at 918-682-8238 or set up an appointment online to get started. Don’t forget to keep Hix Air Conditioning Service, Inc. in mind for oil furnace repairs and maintenance visits. * Annual Fuel Utilization Efficiency (AFUE) measures how efficient the appliance is in converting its fuel’s energy into heat over the course of a year.