Checked carrier heat pump system, system is 7 years old from 2015, unit is running efficiently as of now. Unit is dirty build up of dust and dirt on air movement system and heat media transfer. The duct systems are becoming built of of the same dirt and dust. Recommend joining the Alaskan club VIP maintenance for longevity of system and cleanings of outdoor coil. Second recommendations would be to have a deep cleaning being done to indoor unit as well as duct systems.