A furnace that won’t start at all on a cold Chicago night feels like an emergency, and sometimes it is. But a surprising number of no-heat calls come down to something simple. These checks are safe for any homeowner.
1. Thermostat
Make sure it’s set to Heat and the set temperature is a few degrees above the room. If the screen is blank, replace the batteries. On smart thermostats, check the app for a schedule or “away” mode holding the temperature down.
2. The furnace power switch
Most furnaces have a switch that looks like a light switch, on the wall near the furnace or on the unit. It’s easy to flip off by mistake when reaching for the basement light.
3. The breaker
Check your electrical panel for a tripped furnace breaker. Reset it once. If it trips again, leave it off and call; something is drawing too much current.
4. The air filter
A badly clogged filter can make the furnace overheat and lock itself out. Replace it, then turn the furnace off and on at its switch to reset it.
5. The front door panel
Furnaces have a safety switch that keeps them off unless the blower door is fully closed. If someone changed the filter recently, check that the panel clicked back into place.
6. The condensate drain
High-efficiency furnaces (the ones with white plastic vent pipes) drain water through a tube or pump. If it clogs, a float switch keeps the furnace off. Look for water at the base.
When to stop and call
- You smell gas: leave the house and call Peoples Gas or 911 from outside.
- Your carbon monoxide alarm is sounding: get everyone out and call 911.
- The breaker keeps tripping, or you hear clicking but no ignition.
- The furnace shows a flashing error code after these checks.
Call (312) 924-7223 for furnace repair in Chicago. If the house is getting cold, see what to do while you wait.