Strong chemical or metallic burning smell during furnace operation.

Safety first: Turn off power to the furnace immediately. Do not continue to operate a furnace with a strong burning smell.

• Inspect blower compartment: After allowing components to cool, remove the blower door and look for burned wires, discolored motor housing, or melted plastic.
• Check for foreign objects: Ensure no plastic, foam, or other materials are touching the heat exchanger or burners.
• Do not reset repeatedly: If a limit or breaker has tripped, do not keep resetting without finding the cause.

Electrical burning odors require prompt professional diagnosis to prevent fire or further damage.