I performed heating maintenance on a Lennox Elite EL296 gas furnace in Denton, TX last evening, ensuring it was ready for winter. I started by inspecting the heat exchanger for cracks and cleaning the burners to ensure proper combustion. I replaced the air filter with a 20x25x1 high-efficiency filter and lubricated the blower motor. The flame sensor was polished, and the gas valve was calibrated for optimal operation. Finally, I tested the safety switches and thermostat for functionality. The system passed all diagnostic tests and was running efficiently, providing reliable heating for the customer.