Blue shield plan furnace tune up on Armstrong air 80% gas furnace. Customer has power go out for 2 days earlier this week, otherwise system has been working well. Changed 20x25 filter included with plan. Checked flue and evaporator coil. Checked drain line and gas line. Checked and clean flame sensor. Checked blower, blower capacitor and heat exchanger Turned system on and checked amps and gas pressure. Adjusted gas pressure and replaced caps. Checked carbon monoxide levels. System is operating in manufacturer specs at this time. Spoke with customer about wiring in a generator and surge protectors.