You can fix this
Likely cause: a clogged air filter
Trane and HVAC.com both list a dirty filter as a reason a furnace won't ignite or won't stay on. A new filter is the first fix to try.
Why this happens
When the filter clogs, the furnace can't move enough air and its safety controls may stop it from lighting or shut it down early. Trane and HVAC.com both recommend replacing the filter every 1 to 3 months.
How to fix it
- Set the thermostat to Off before you pull the filter.
- Replace the filter with the same size, arrow pointing toward the furnace.
- Set the thermostat back to Heat and wait a couple of minutes for the furnace to start.
- Write the date on the new filter's edge so you know when it's due again.
When to stop. If it still clicks without lighting on a clean filter, call an HVAC technician.
If this does not fix it, tell the HVAC technician
- How dirty the filter was and when it was last changed.
- Whether the furnace lit after the new filter.
- Whether you heard clicking before you changed it.
Build the full list: what to tell the HVAC technician.
Start this troubleshooter over
References (every fact above comes from one of these pages)
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