Issue with furnace not coming on,no continuity at fuse panel

Mugsysiegel

Advanced Member
Joined
Apr 20, 2023
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30
Location
North Texas
So I have a Suburban SFV 35q. The furnace went out last year and we didnt have time to mess with it. Well recently we found a pex connector leaking on soft hose and low and behold its above the control board. Some green corrosion is visible on board also. I tried to turn furnace on. The fan comes on and blows cold air,than after a few seconds just turns off. So I checked the fuse panel when I pull ANY fuse besides the furnace fuse I get a red indicator light on panel. Also no continuity on the furnace fuse or the actually part it slides into. Now I know I most likely need the board but would the board being bad make me lose continuity at the fuse panel also? Anything else to check? For anyone that has replaced the control board is it best to go oem route or get the dinosaur electronics one? Tia
 

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I would check that your sail sw is functional before I bought the board. Water leaking on your control board likely killed it but it's not a guarantee. Your symptoms would point to a sail sw not making.
Dinosaur electronics seems to have a good rep.
 
So I have a Suburban SFV 35q. The furnace went out last year and we didnt have time to mess with it. Well recently we found a pex connector leaking on soft hose and low and behold its above the control board. Some green corrosion is visible on board also. I tried to turn furnace on. The fan comes on and blows cold air,than after a few seconds just turns off. So I checked the fuse panel when I pull ANY fuse besides the furnace fuse I get a red indicator light on panel. Also no continuity on the furnace fuse or the actually part it slides into. Now I know I most likely need the board but would the board being bad make me lose continuity at the fuse panel also? Anything else to check? For anyone that has replaced the control board is it best to go oem route or get the dinosaur electronics one? Tia
Kind of odd that the fan ran but the fuse has no continuity.

You won't (shouldn't??) get continuity between the fuse holder blades; but one side should have 12v on it when there is no fuse present.

If you pull a fuse on the DC fuse panel and the light doesn't light it means there is no active device on that circuit and no path to ground either (no short circuit). This video is invaluable in understanding how that indicator light (and fuse circuit) works.

Since the fan comes on I'd say you are getting 12v to the furnace. But it has probably shut off (and therefore not demanding any current) when you pulled the fuse and found that the light didn't come on. I guess it's complicated. Check the video.

I'd go with the dino board if it is less $$ than the OEM. But look the board over first to see if a printed circuit path got broken when it got corroded; you may be able to fix that.
 
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I would check that your sail sw is functional before I bought the board. Water leaking on your control board likely killed it but it's not a guarantee. Your symptoms would point to a sail sw not making.
Dinosaur electronics seems to have a good rep.
I will just put a meter on and continuity test it when I actuate it closed right? I pulled it out it was spotless no hair on it nada. The board is green with corrosion. EDIT I tested the sail switch it works great
 
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This is how corroded the board is. The water was running directly onto it.
 

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Continuity testing can fool you since it’s a very low current test. Measuring voltage on both sides of the fuse, both with the furnace on and off, would tell you more.
 
For anyone that has replaced the control board is it best to go oem route or get the dinosaur electronics one? Tia
After replacing two hot water heater circuit boards in a two year period (both were OEM), I went with Dinosaur Electronics. 5 years now and no issues! It is my opinion you cant go wrong with this company. They are well made circuit boards and have an outstanding warranty!
 

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