Originally Posted by Hauffhouse
My flashing LED indicates an open pressure switch. Where is this switch and does it need replacement or just resetting? It also indicates that it could be a blocked condensate drain. (I am not familiar with the location of either of these) Any ideas/thoughts? Thanks.
this "code" is simply letting you know that the pressure switch did not close. Normally when the furnace is not running the switch is what we call "normally open", when the t-stat calls for heat and the draft motor starts it pulls the pressure switch closed, this MUST happen for the ignition sequence to be completed.
Several things can keep the pressure switch from closeing.....if the ventor motor does not start, the pressure switch will not close, if the flue pipe of even the throat of the ventor is plugged the pressure switch will not close. If the proving tube (usually connected to the draft motor housing or the burner box is plugged or obstructed the pressure switch will not close.......finally and the rarest situation.......the switch its self is bad.
Typically a trained service technician will use a magnihelic Gage and or a manometer to determine the root of the problem.