Miller
Overheating / Inadequate Airflow
Furnace cabinet becomes excessively hot to the touch during operation.
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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
Blocked return air, Dirty filter, Blower running at too low speed, Undersized duct system
How to Fix / Troubleshooting
Safety: Turn off power before accessing blower or wiring. Overheating can damage components and pose a fire risk.
- Restore airflow: Replace filters, open all returns and supplies, and clear obstructions.
- Check blower speed tap: On the Miller control board or motor wiring, verify the blower is set to the recommended heating speed. Increase speed if necessary per Miller documentation.
- Inspect ducts: Look for undersized or restricted duct runs. Consider having a professional perform a duct evaluation.
- Monitor cabinet temperature: After corrections, run the furnace and ensure the cabinet remains warm but not dangerously hot.
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Repair Difficulty
Medium
3/5
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