Danfoss
Airflow Restriction / Blower Failure
The 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 the shaft, closed fire dampers.
How to Fix / Troubleshooting
Safety first: Turn off the 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 the power off, verify that the blower wheel is firmly attached to the motor shaft and not spinning freely on 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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