I was hired to perform heating maintenance on two Trane systems. The first system was a gas furnace with an air conditioner. The second system was a gas furnace with a heat pump. During the maintenance, I changed the main level filter, cleaned the upstairs filter, and checked the heating performance of both systems. I also took before and after pictures of the units to show the improvements. After the maintenance, the systems were heating properly and the homeowners were satisfied with the results.