During the furnace service, I identified that the air filter was excessively dirty, which was impeding system performance. Additionally, the flame sensor was coated with grime, affecting its efficiency. I meticulously cleaned the flame sensor, restoring its functionality. I advised the client to replace the air filter to ensure optimal system operation. After these adjustments, the furnace functioned correctly. Given the system's age, I recommended a comprehensive visual inspection of the heat exchanger during our next scheduled maintenance to preemptively address any potential issues with integral components.
