Fraser-Johnston
Insufficient Airflow or Duct Restriction
Furnace runs but some rooms are cold; weak airflow from certain 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
Dirty blower wheel, Collapsed or disconnected duct, Closed balancing dampers, Undersized return ducting
How to Fix / Troubleshooting
Safety first: Turn off power before accessing blower or ducts.
- Inspect blower wheel: Remove blower assembly and clean dust buildup from the wheel blades with a brush and vacuum.
- Check accessible ducts: Look in the basement or attic for crushed flex duct, disconnected joints, or closed dampers. Open any manual dampers that are closed.
- Verify filter type: Ensure the filter is not overly restrictive for your system. High‑MERV filters may require duct modifications.
- Professional duct evaluation: Persistent airflow imbalance may require duct redesign or zoning by an HVAC contractor.
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Repair Difficulty
Medium
3/5
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