What does furnace making a loud noise (banging or scraping) mean?
Scraping or grinding usually points to a blower wheel hitting debris or a failing motor bearing. Banging on startup can be delayed ignition — a dangerous condition where gas builds before lighting. Either warrants prompt professional attention.
What usually causes furnace making a loud noise (banging or scraping)?
Failing blower motor or wheelmost common
Typical repair: $450–$1,200
Delayed ignition bangingcommon
Typical repair: $150–$400
Loose access panel rattlingpossible
Typical repair: $300–$800
Find your exact error code
Select your furnace brand to jump to the code page for this symptom.
What should I check first when furnace making a loud noise (banging or scraping)?
- Turn off the furnace if you hear scraping metal on metal.
- Check that all access panels are seated and latched.
- Do not ignore banging at ignition — call a licensed technician.
- Note when the noise occurs (startup, running, shutdown) for the tech.
What a repair costs
A blower motor replacement typically costs between $450 and $1,200 nationally.
Typical repair cost
$450 – $1,200blower motor replacement
Where the money goes
Part $150–$500Labor $0–$1,050Typical labor time: 2–4 hrs
This is general information, not professional advice. Gas, electrical, and combustion repairs can be dangerous — when in doubt, call a licensed technician.