79
Ruud
Fan Motor Current Abnormal / Overcurrent
Ruud tankless water heater displays error code 79; unit may shut down unexpectedly.
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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
Fan motor drawing excessive current due to mechanical binding, Shorted fan motor windings, Control board fan driver fault, Blocked fan wheel
How to Fix / Troubleshooting
Safety first: Turn OFF power and gas. Avoid contact with sharp fan blades.
- Step 1 – Inspect fan wheel: Remove the front cover and check the fan for debris or damage. Ensure it spins freely by hand.
- Step 2 – Check wiring: Inspect the fan motor harness for shorts or melted insulation. Reseat the connector.
- Step 3 – Replace fan assembly: If the fan is stiff or shows signs of overheating, disconnect wiring, remove mounting screws, and install a new OEM Ruud fan assembly.
If error 79 persists with a new fan, the control board may be faulty and should be replaced by a technician.
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Repair Difficulty
Hard
4/5
Required Part
Combustion Fan Motor Assembly
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