Performed a complete heating system maintenance and inspection 2018 heat pump. Inspected and tested all electrical components and safety controls on the indoor unit; all components tested within manufacturer specifications. Verified system temperatures: return air temperature measured at 77°F; supply air temperature measured at 104°F and rising. Confirmed air filter was needing to be replaced. I replaced he filter on today’s visit; filter size is 20” x 20” x 1”. Inspected and tested all electrical components on the outdoor unit; all components tested within manufacturer specifications. Confirmed system was operating properly and heating upon departure. System Status: Operating normally at time of service.