check the blades of the fan are clean and not covered in dust
erj
January 2010
possibly the fan is failing and not running fast enough to make the aps connect or having difficulty drawing air due to a blockage in the air intake part of the flue. make sure the red and white rubber tubes going to the air pressure switch dont have any holes or tears in them and no blockages in the venturi micro tubes
john
January 2010
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