The Normal Dust Smell
It happens every fall. We get the first chilly night in Greater Cincinnati or Northern Kentucky. You switch your thermostat from cool to heat. Ten minutes later, the whole house smells like a campfire. Don't panic. Dust settles on your furnace burners and heat exchanger all summer. When you turn the heat on, that dust burns off. The smell should disappear in a few hours. Open a window if it bothers you.
Burning Plastic or Rubber
A burning plastic smell is different. That is not normal. It usually means a foreign object found its way into your ductwork or furnace. Kids drop toys down floor vents all the time. If the smell is like burning rubber, the blower motor belt might be slipping or melting. Turn the furnace off right away.
Electrical Burning Smells
If the smell reminds you of burning wire insulation or an overheating motor, you have an electrical problem. The blower motor could be burning out. A relay switch might be melting. Electrical fires are dangerous. Shut the system down at the thermostat. Then turn off the breaker to the furnace in your electrical panel.
Check Your Air Filter
A completely clogged air filter forces your furnace blower motor to work too hard. The motor overheats and starts to smell like hot metal and burning wire. Pull the filter out. Hold it up to a light. If you cannot see light through it, throw it away and put a new one in.
What to Do Next
If the smell is dusty, wait it out. If it smells like plastic, rubber, or electrical wires, leave the system off and call us. We will come out for an $89 diagnostic fee to track down the burning odor. With our Repairs First policy, we find the melted wire or bad motor and fix it. We never use a scare tactic to sell you a new furnace.