Combustion Air Blower Problem - Self Help Forums

This is more known as your inducer. 3 things will slow it down, bad bearings or motor failure (sounds like you have addressed this already), restricted exhaust or intake or a problem on your control board (burnt relay contacts). Check your exhaust and inlet to make sure it is all clear. If that is good then your board probably needs replaced. Trace the wiring and make sure it goes straight to the board. The relay could be elsewhere (not common but may saves you from replacing the board). If you know someone who does electronics repair, they may be able to replace the relay for you.

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