Dispatched for a furnace that was not operating. Upon arrival, the furnace was found in a safety lockout due to a rollout switch fault, indicating the system detected abnormal flame conditions and shut down to prevent a potential fire hazard. After resetting the furnace and performing a controlled restart, the system was monitored through the ignition sequence. It was determined that burner chamber #1 had an unstable flame pattern, with the flame flickering and pushing outward from the chamber instead of remaining properly drawn into the heat exchanger. This condition is consistent with flame rollout, which can cause excessive heat buildup inside the burner compartment and repeatedly trip the rollout safety switch. During the inspection, the following diagnostic steps were performed: • Checked flue venting for proper draft • Verified inducer motor operation and confirmed proper amperage • Inspected burner assembly for any clogs, debris, or restrictions • Checked and verified gas