Furnace tune-up and safety inspection. Cleaned and serviced furnace. Tested all mechanical components. Found ignitor and flame sensor very corroded, and the customer agreed it was time to replace. Cleaned all pressure switch hoses. Tested gas valve voltage and pressures. Replaced the furnace filter that the customer provided. (AprilAir 410). The system is clean, heating, and operating properly at this time. The customer also renewed the VIP maintenance plan. Performed free plumbing inspections.