I am a home service technician, and I recently completed a furnace maintenance job. The furnace was not producing heat, so I checked the system's operation and found that the flame sensor was dirty, causing the furnace to shut off. I cleaned the sensor and checked the amp draw of the blower and inducer motor, which were both within normal ranges. I also checked the air filter and found that it was dirty, so I replaced it. After completing the maintenance, the furnace was producing heat again, and the customer was happy with the results.
