If your furnace will not light, a few safe checks can solve the simplest causes. If you smell gas, leave the house and call PG&E or 911 from outside. Do not operate switches or try to light anything.
Safe Checks First
- Confirm the thermostat is set to heat and above room temperature, and replace its batteries.
- Check that the furnace power switch, which looks like a light switch near the unit, is on.
- Check the circuit breaker for the furnace.
- Replace a clogged air filter; some furnaces shut down when airflow is blocked.
- Make sure the furnace door is closed fully; a safety switch stops the furnace when it is open.
What the Symptoms Usually Mean
- Clicking but no flame: often the igniter or gas supply to the burners.
- Lights, then shuts off after a few seconds: often a dirty or failing flame sensor.
- Inducer runs, but the furnace never lights: often a pressure switch or venting problem.
- Nothing happens at all: power, thermostat or a control board issue.
When to Call
If the safe checks do not fix it, book a diagnostic. An Aarvaks technician finds the failed part and gives a written repair quote. The residential diagnostic is $79, waived if we do the repair. Furnace repair · book online
Frequently Asked Questions
Why does my furnace click but not ignite?
Clicking without a flame often points to the igniter or the gas supply to the burners. A technician can test both safely.
Can I reset my furnace?
Turning the power switch off for a minute and back on resets many furnaces. If it locks out again, a part has likely failed and needs a diagnostic.
What should I do if I smell gas?
Leave the house, then call PG&E or 911 from outside. Do not use switches, phones or anything that could spark inside.