Burners ignite briefly then shut off; LED flashes 4 times repeatedly; blower may run with no heat.

Safety: Turn off power before removing panels. Metal edges can be sharp; wear gloves.

Steps:

• Check and replace the furnace filter. Tappan furnaces are very sensitive to low airflow; a clogged filter is the most common cause of limit trips.
• Ensure all supply and return vents in the home are open and not blocked by furniture or rugs.
• Locate the high limit switch on the heat exchanger panel. With power off, check for continuity across the switch. If it is open at room temperature and does not reset, replace the limit switch.
• Observe the blower operation during a heat call. If the blower starts late, runs slowly, or does not run, the blower motor or capacitor may be failing, causing overheating.
• After correcting airflow issues, reset power and monitor a full heat cycle to confirm the code does not return.

Note: Repeated limit trips can damage the heat exchanger; if the problem persists, have a professional check static pressure and duct sizing.