Dispatched for a routine furnace tune-up. Upon arrival, a full inspection and operational test of the system was performed. All safety components—including the pressure switch, flame sensor, limit switches, and rollout protections—were tested and found to be operating within manufacturer specifications at this time. During the inspection of the heat exchanger, visible signs of pre-failure conditions were noted. This includes rust forming around the inlet ports and corrosion developing on the eyelets. These conditions are important to monitor closely, as the heat exchanger is responsible for safely separating combustion gases from the air circulated throughout the home. Heat Exchanger Explanation: Over time, exposure to heat, moisture, and combustion byproducts can cause metal fatigue, rust, and corrosion. As these conditions progress, they can lead to cracks or openings in the heat exchanger. A failed heat exchanger may allow flue gases—including carbon monoxide—to mix with the house