Performed semiannual maintenance on two gas furnace systems. Inspected all Performance, Mechanical and Safety Systems. The homeowners mentioned that the master bedroom would get extremely warm when the bedroom door was closed off. I made some adjustment to the damper that supplies the home run duct to the supply grille that is in front of the master bath doorway. I asked them to try it out during the cold spell next week and let us know if they continue having issues. Current filters installed were still in clean condition. Verified everything was operating within manufacture’s specifications for operation. Everything is working at this time. See attached checklists for full tune-up details.