Furnace pressure switch line/nipple question


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Old 12-30-11, 12:57 PM
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Furnace pressure switch line/nipple question

I recently had my inducer/exhaust fan replaced and several times since have found the new inducer fan running but the unit wouldn't fire up. On investigating I find that there are three hoses to the pressure switch. One is marked "-" and is attached to the inducer fan housing. The second marked "+" and connected to the "ignition box" (right name?). The third connects indirectly to the pressure switch by a "T" to the same place on the "ignition box" as the "+" hose, and is then connected to the "gas regulator" (right name?).

The non-flame up only happens occasionally, and can be overcome by sucking on the hose attached to the negative nipple.

Important point: The hose to the pressure switch that connects to the nipple marked "+" has a small plastic plug in it, that fits up into the nipple but cannot enter the nipple because of a small flange on the plug. The hose will fit over this grey plastic plug. This plug has a slot shaped hole in the flange end and a long slit and rectangular opening on the long shaft of the plug itself. Air can move through this plug.

Finally, here is my question: Is this plug a functioning piece of the pressure switch? Or just a leftover piece from when it was packaged?
 
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Old 12-30-11, 02:46 PM
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Bump!

Nobody has ever heard of this? Surely someone has seen this little grey plug before! If it regulates pressure on the "+", and I take it out, what will happen.

Even negative replies are welcome ("I've never seen/heard of this plug before."). If no one has ever, ever seen this before then I will feel better taking it out and seeing if it fixes the problem.
 
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Old 12-31-11, 03:46 AM
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it is part of the pressure switch and is required! A few questions. Is there a diagnostic code on the control board? Led flash? I'm assuming if you have a code it is a 3 flash. But I want to confirm this before going any further in the Diag. Please post the make and model of the furnace also.
 
 

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