Hi, I have a ~5yr old intertherm furnace whose lights indicate 'pressure switch stuck open'. I checked the hoses for blockage, and in doing so, can't be sure which hose went where.. (silly me).One hose, as you may know goes to the inducer through the backplate, and the other splits to the Gas valve and the (combustion compartment?).. The hoses connect to the pressure switch one behind another. (with the connectors facing you, and the mounting bracket facing away. The only distinguishing feater is the front connector has a light blue collar inside..

So.. Does it make a difference which hose attaches where And if so, where might that be

TIA

I figured it out, The rearmost connector on the p.switch (closest to mounting bracket) requires suction, and goes to the inductor via the backplane.. The foremost connector (while teminals are facing you, and has light blue collar) receives backprussure from both the gas valve and the combustion chamber.
I already had these properly connected. The trouble was a clogged connector and the backplane. I shove a nail in there and cleared him out good..
YAY HEAT \O/

I know your post is from a while ago, but maybe still around. When you said a clogged connector, which part do you mean? The pressure switch has a plastic "nipple" that the rubber hose connects to. Do you mean the hose or the "nipple"? I put a wire through both, but didn't ram it in there like you with that nail being afraid that I may break something. The wire I put into the "nipple" only went as far as the length of the "nipple". The wire through the hose went through easily and nothing came out. So, do I need to really ram something into the "nipple"? The wire I put in there also came out totally clean.

Hope you get this,
Ceci

Hi.. Yeah this was a few years back, I wouldn't suggest 'ramming' it per se, but it did require a firm push. My problem was the 'nipple' of the backplane was clogged with a clacified-like build up. The hoses were fine. If this is your problem, the wire should be able to go beyond the end of the nipple (ON THE BACKPLANE).. I would be wary of going beyond the nipple of the connector though.. Probably a fragile thingy inside it..

HTH Good luck.

Oh thank you for replying, but I am a bit confused. I think you have the high efficiency unit so bit different setup than mine. Mine is a medium efficiency one, but many things the same from my understanding(limited). I only have one hose(rubber) that goes into the pressure switch through this little, little plastic "nipple" and the hose connects to the fan thing(draft inducer, I think, it's called). So, what do you mean "backplane"? Backplane of what? When you said the "nipple", do you mean the plastic "nipple" of the pressure switch? Confused me about that other thing you said(beyond the nipple of the connector). What is a connector? :) Weird thing happened today, it went on without me fiddling with it for quite a while and then again not working. I really think it is something simple so don't want to call a company since they will charge an arm and a leg and this thing is 15 years old and already put 600 so should really replace the heat and air conditioning units instead of shelling out more money(some outside part for the air unit died about 2 years ago and about 15 months ago had a clogged water hose which caused the water to drip all over when I had the air on which the guy misdiagnosed and put in a new pump instead which was actually not broken so then had to come back 2 hours later again since lots of water was dripping out of the unit-inside the house part and then that stupid new pump just broke recently so I put in the old pump which really wasn't ever broken since I tested it after he left to figure out how these things work). Were you able to follow that? I don't think me putting the old pump back has anything to do with the furnace going wacko, but what do I know. Anyway, please clarify what you said.

Thank you, thank you,
Ceci