Like to the the OP for returning to let us all know the final outcome. Thanks evilsanta.
So many of these head scratching posts just end up with no resolution.
Thanks OP for posting the fix. I had a furnace with a similar problem last week. It was dropping in and out intermittently, so another tech replaced the door switch. A week later I'm sent out on a follow up, talk to the homeowner she says it didn't work earlier today, but now it's working again. I check for codes don't see any, so I tape the switch everything works fine, put the door back on, here comes the problems again. I check the switch it's fine. I finally figure out that the r stat wire wasn't tightly screwed down, and whenever the door was put back on it would push the wire just enough so that it would intermittently lose contact.
I had one years ago that I suspected had a bad pressure switch. After replacing it, and problem did not go away found a wasp nest in the flue pipe. Did I feel stupid over that. However I will never forget it. Now I stay away from residentual work, you guys can have it. Good luck and God Bless
It very well could be that the board is bad, however I have seen something similar to this. It is possible that there could be a low voltage short or a loose connection either on the board or in the wiring that wouldn't cause a fuse to trip, but to cycle like this.
Last summer I observed a short in a contactor coil. When the Thermostat (Honeywell 5000) would come out of its time delay and energize (Y) causing the short, the thermostat would flicker then cycle back into its time delay and never trip the low voltage fuse. I observed this happening about 4 or 5 times in a row. I ohmed the contactor out, found it shorted to ground, change the contactor, and everything was fine, we haven't been back since.
I would at lease make sure all your connections where good. and no nicks in the wiring. Just a thought.
A good lesson to learn is 90% of the time you get a pressure switch code it's not the switch. Maybe not 90 but close.
I'm starting to think this might not be as true as it used to be, perhaps due to the increased presence of 90%ers and the water fouling contacts? Have to ask our neighbors to the north...
I've already caught a couple more this year over last on 80%ers.
Or maybe just like everything else...someone found a cheaper way to make junk.
A good lesson to learn is 90% of the time you get a pressure switch code it's not the switch. Maybe not 90 but close.
I finished up a class last week with Johnstone on MODULES
Class was told that 99% of switch sent back tested A-OK
DON"T mess with the US
I thought I had been there and done That.
ITS ALL ABOUT LEARNIN!
I thought it would be better by now
"He who works with his hands is a laborer.
He who works with his hands & his head is a craftsman.
He who works with his hands, his head & his heart is an artist."
~St. Francis of Assisi
I,m wondering why the inducer does not continue to run even thou the pressure switch fails to close.
Seems to me its safer to have it run than stop,the board should then keep the ignighter from lighting,.
That would definetly make you look at pressure switch and igniter FIRST
Watching the Video Made me think like others that it was Power Related
DON"T mess with the US
I thought I had been there and done That.
ITS ALL ABOUT LEARNIN!
I thought it would be better by now
"He who works with his hands is a laborer.
He who works with his hands & his head is a craftsman.
He who works with his hands, his head & his heart is an artist."
~St. Francis of Assisi
I,m wondering why the inducer does not continue to run even thou the pressure switch fails to close.
Seems to me its safer to have it run than stop,the board should then keep the ignighter from lighting,.
That would definetly make you look at pressure switch and igniter FIRST
Watching the Video Made me think like others that it was Power Related
I agree. When P/S's fail to close the inducer keeps running till the board shuts it down and throws an error - takes a full minute and change on most furnaces. I'm assuming the pressure switch closed and then quickly reopened - prompting an immediate shut down. But this should not be. The blower and inducer should continue to run if the P/S breaks in the middle of a cycle. In fact, is it not even more imperative that they continue run if a safety opens in the middle of a cycle as opposed to the very beginning of a cycle? Matter of fact, the P/S is on the gas valve circuit along with the limits, rollouts etc and should have nothing to do with the inducer...
Dammit! I've second guessed myself back to the board and 1. it's not even my job & 2. the issue has apparently been resolved!
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Originally Posted by Joehvac25
