Danfoss
Airflow Restriction / Blower Failure
Furnace fan runs but there is little or no airflow from the registers
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Safety Warning
This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.
If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.
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Possible Causes
Collapsed duct, disconnected duct, severely clogged filter, blower wheel loose on shaft, closed fire dampers
How to Fix / Troubleshooting
Safety first: Turn off power before inspecting ducts or blower.
Steps:
- Check filter: Replace any heavily clogged filter immediately.
- Inspect accessible ducts: Look in the attic, basement, or crawlspace for disconnected or crushed ducts. Reconnect and support as needed.
- Check blower wheel: With power off, verify that the blower wheel is firmly attached to the motor shaft and not spinning freely without the shaft.
- Fire dampers: In commercial or multi-unit buildings, ensure fire dampers have not closed and locked due to a false alarm.
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Repair Difficulty
Medium
3/5
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