# Concord 80 Plus furnace issues



## Angry Snail (Oct 8, 2013)

Hi all, glad I found this site as there seems to be quite a few DIY pro's here. 


I have a Concord 80 plus furnace that is not working, and by that I mean it isn't doing ANYTHING. No clicks, beeps, etc.... except for a continuously blinking green light. 

I have messed with the thermostat, turned it down, off, replaced the batteries, etc.....Flipped the switch on the side of the furnace, reset the breaker.

I would think, and I don't know if this is right, that the furnace should make some noise when it attempts to start - I get nothing. I've had my wife fuss with the thermostat while I sit down there staring blankly at the internals of a furnace and nothing happens at all. I am pretty sure after researching that it has some sort of auto pilot light (there's no pilot light anywhere to be found), but nothing glows or ??? is supposed to happen. This thing is dead in the water except for that blinking green light. It doesn't appear to be a fault code of any sort because it blinks continuously and never stops. I work on cars and computers, i'm able to read and understand fault codes - unless a non stop blink is code for something i'm lost. 

Any ideas? I'm going to take the flame sensor thingamabob out and clean it but I don't know how that will help as it currently never sees flame to begin with. 

New filter is in BTW.


Thanks


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## ben's plumbing (Oct 6, 2011)

Angry Snail said:


> Hi all, glad I found this site as there seems to be quite a few DIY pro's here.
> 
> 
> I have a Concord 80 plus furnace that is not working, and by that I mean it isn't doing ANYTHING. No clicks, beeps, etc.... except for a continuously blinking green light.
> ...


 you need to see how many times it blinks for the fault code......power down the service switch and turn it back on and observe furnace it should restart...ben sr


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## Angry Snail (Oct 8, 2013)

Thank you for the response Ben, I have powered the furnace down several times, the fault code light blinks constantly - it does not stop at a "count". Meaning, I could count the blinks infinitely if I sat there. Dim, bright, dim, bright, dim, bright ~

The lower part of the furnace I just noticed (i'm guessing that's a fan down there?) hums ever so quietly. 


Hope that helps, sorry for the vague details but that's all I have to go on right now.


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## beenthere (Oct 11, 2008)

With the power turned off, run a jumper from the R terminal to the W terminal on the furnace control. Then turn power back on and see if it runs(with the panel back on).


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## Angry Snail (Oct 8, 2013)

Thank you for the help - is the furnace control the unit that contains the blinking light? 

I'm sorry, you are dealing with a complete idiot when it comes to these things, i'm not sure what a furnace control is. 

Do not worry, I am "handy", I just do not know the terminology.


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## beenthere (Oct 11, 2008)

Yes, the board with the blinking light is the furnace control board.

Sorry, but I got called out shortly after I posted earlier, and by the time I gone done and back home. I was ready for bed.


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## PoleCat (Sep 2, 2009)

Angry Snail said:


> ............
> The lower part of the furnace I just noticed (i'm guessing that's a fan down there?) hums ever so quietly...........


Idle fans shouldn't ought to hum. Maybe that is the transformer you are hearing?


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## ben's plumbing (Oct 6, 2011)

I believe that has a honeywell smartvalve in it ....which is what you are seeing blinking...or as you say bright dim,bright dim..which is normal ..do as been said in lower compartment jumper r to w then hold in door switch see if it starts....if it does problems in thermostat or it wiring...ben sr


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## Angry Snail (Oct 8, 2013)

Thanks guys, here's what i've done so far. 

Replaced batteries in thermostat = no change
Jumped wires @ thermo stat = no change

With wires jumped at thermostat:

Checked voltage on board between R & W = 0 volts

Unplugged inducer motor and checked voltage at harness to board = 0 volts

Checked voltage between R & C on board = 27 volts

Everything checked with wires jumped at thermostat and panel door switch held shut. 

Anything else to check? Any ideas? There is no "manual" lighting of the pilot on this thing that I can see. 

Filter replaced and squirrel cage moves freely.


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## Angry Snail (Oct 8, 2013)

Should I jumper R & W at thermostat or actual furnace board? 

I have the red and white wires coming out of the wall twisted together right now.


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## ben's plumbing (Oct 6, 2011)

Angry Snail said:


> Should I jumper R & W at thermostat or actual furnace board?
> 
> I have the red and white wires coming out of the wall twisted together right now.


 take those wires loose at the board ...and jump r to w ..see if unit starts...ben sr


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## Angry Snail (Oct 8, 2013)

Thanks ben, heading down there to do this right now.


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## Angry Snail (Oct 8, 2013)

Placed jumper wire between R & W on furnace circuit board, turned furnace on and held the door switch closed = nothing happened


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## ben's plumbing (Oct 6, 2011)

Angry Snail said:


> Placed jumper wire between R & W on furnace circuit board, turned furnace on and held the door switch closed = nothing happened


 is there a 24 volt fuse on control board 3-5 amp ...have to leave on a call will be back around 9-930 ...pics would help.. ben sr


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## ben's plumbing (Oct 6, 2011)

make sure power is on and door switch closed ...measure voltage between r - and c ...ben sr


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## Angry Snail (Oct 8, 2013)

Very dirty and dusty, first time i've ever opened this furnace so i'm going to blow the board off, clean it up a bit and i'll look at it, take pics, etc.....


Ben I really appreciate the help and knowledge that you're giving me. Working on race cars and computers my entire life I can appreciate someones help!


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## ben's plumbing (Oct 6, 2011)

Angry Snail said:


> Very dirty and dusty, first time i've ever opened this furnace so i'm going to blow the board off, clean it up a bit and i'll look at it, take pics, etc.....
> 
> 
> Ben I really appreciate the help and knowledge that you're giving me. Working on race cars and computers my entire life I can appreciate someones help!


 your very welcome will check back.... go over all the post again and see if you may have missed something...ben sr.....


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## Angry Snail (Oct 8, 2013)

There's a fuse on the board, wasn't bad but I went ahead and replaced it anyway. Here's what i'm trying to work with



































Here's a video of the LED light and what it does when I hold the panel door shut


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## Angry Snail (Oct 8, 2013)

In the meantime I have just cleaned the flame sensor? along with the ignitor? 

Rigged the blower motor into the door safety switch to make sure the blower motor worked - it does. 

Nothing has helped. Seems like a signal isn't getting from the board to something - or from that valve with the blinking LED to something. 

Board is getting power, that much is certain. I'm not sure it's sending power out to something but I don't know how to verify that.


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## firedawgsatx (Jul 15, 2013)

First thing I notice is that you don't have any wires from the thermostat connected to your board. Did you remove them for cleaning or there aren't any wires attached? There should be thermostat wires attached in the circled area on the board.


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## beenthere (Oct 11, 2008)

Angry Snail said:


> In the meantime I have just cleaned the flame sensor? along with the ignitor?
> 
> Rigged the blower motor into the door safety switch to make sure the blower motor worked - it does.
> 
> ...



Use meter and see if you read 24 volts or more from the R terminal to the W terminal on that board with the safety switch closed. If so, then run a jumper wire from the R terminal to the W terminal, and close the door safety switch again, and see if it runs.


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## Angry Snail (Oct 8, 2013)

Ben had me jump R & W earlier, it didn't help. 

The wires for the thermostat were off for that reason. 

Voltage between R & C was 27

How do I check voltage to the draft inducer motor? Seems like that thing needs to run in order to move onto the next step in startup?


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## beenthere (Oct 11, 2008)

With the R and W jumpered, you check to see if there is 120 volts on the terminals that the inducer connect to.


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## Angry Snail (Oct 8, 2013)

Just went down and checked the Honeywell valve, seems it controls the inducer fan. There's a 4 pin plug that gets power from the control board, those 2 wires are getting 118 volts to it. The other 2 wires in that plug assembly go to the wiring harness for the inducer, there's 0 volts in those 2 wires. Is there something inside the valve that tells the inducer motor to turn on? 

Is it possible this is a bad valve?


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## Angry Snail (Oct 8, 2013)

0 volts to the inducer harness while jumpered


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## beenthere (Oct 11, 2008)

Bad inducer relay on the board. Replace the board.


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## ben's plumbing (Oct 6, 2011)

can we see picture of the valve that has the green light on it ....als jiggle those wires on the smartvalve may be loose....ben sr


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## ben's plumbing (Oct 6, 2011)

you can try gently tapping the little black relays on the control board have seen these stick....but would mean still needs replaced...


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## Angry Snail (Oct 8, 2013)

The valve is a Honeywell SV9520H, I have video of it above showing the green light. I'll try tapping the relays. 

Would a limit switch cause this? 

I've unplugged/plugged/jiggled the harness from the valve/inducer several times with no luck.


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## Angry Snail (Oct 8, 2013)

Thanks beenthere - didn't see your post. You think it may be board related then?


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## ben's plumbing (Oct 6, 2011)

Angry Snail said:


> The valve is a Honeywell SV9520H, I have video of it above showing the green light. I'll try tapping the relays.
> 
> Would a limit switch cause this?
> 
> I've unplugged/plugged/jiggled the harness from the valve/inducer several times with no luck.


sorry i see the top of the valve ...is the switch on...don't laugh I worked on one a few yrs back for about 45 min ..only to find the switch on the valve off...ben sr


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## Angry Snail (Oct 8, 2013)

hehe, yes sir switch is on :thumbsup:


I work on computers as a 20 year IT tech, the stuff i've seen..........


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## ben's plumbing (Oct 6, 2011)

look at this


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## Angry Snail (Oct 8, 2013)

That's it right there. Shouldn't that inducer motor have power if the other 2 wires in that C3 plug are hot with 120v? Or is there something in that valve or on the board that sends power to the motor? 

Am I even on the right track with this inducer motor? Is that the first step in startup sequence? I'm trying to move step by step and see if I can figure this out.


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## ben's plumbing (Oct 6, 2011)

start up....stat calls for heat...small click that is pullin in relay on board.. inducer starts proves pressure switch, ignitor starts.. gas valve opens.. burnners fire.. flame sensor proves there is flame.. blower comes on warms house shuts down stat...that is the basic set up there are some safety switches involved and a limit ...ben sr


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## ben's plumbing (Oct 6, 2011)

you could pull the leads off inducer and apply 120 directly to see if inducer will run???ben sr


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## Angry Snail (Oct 8, 2013)

Bleh, lol, that sounds like the board then? I don't get that click, i've checked for that as well.


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## Angry Snail (Oct 8, 2013)

I may do that tomorrow, i'll get some alligator clips and give that a try


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## ben's plumbing (Oct 6, 2011)

if your sure of your voltage checks ....change board...ben sr


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## Angry Snail (Oct 8, 2013)

Ben - power (118v) comes out of the board and into a 4 way plug at the gas valve, the 2 wires coming from the valve to the inducer motor never has voltage no matter what i've tried. 

Is there something on the board that tells the valve to supply those wires with voltage for the inducer motor or does this sound like something is messed up in the smartvalve? 

Sorry for the questions, i'm ready to order the board but the OCD in me needs to know how this stuff works when I start messing with it. 

Power in from breaker to small light switch on side of furnace. Power from that switch straight to the board, from board into smartvalve (118v), wires supplying inducer never get voltage so inducer never starts....Does the valve need to see something from the board to allow power out of the inducer wires? 

Thanks


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## yuri (Nov 29, 2008)

try this honeywell link there are some pdf files with specs and troubleshooting (installation info). the board is a fan timer board (ST9100, get the number off the sticker on yours) and part of the loop, find its info too.

go products>.residential

https://customer.honeywell.com/en-US/Pages/default.aspx


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## firedawgsatx (Jul 15, 2013)

> the 2 wires coming from the valve to the inducer motor never has voltage no matter what i've tried.


There should be two wires going from the inducer motor to the control board. Follow them from the inducer to the board and disconnect these two wires from the board. Put one probe from your meter onto each terminal of the board and turn the furnace on with a call for heat. You should, in less than a minute get a reading of 120 volts on the meter. If you do not, the board is probably bad.


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## Angry Snail (Oct 8, 2013)

The 2 wires from the inducer to board actually go from inducer to smartvalve, from smartvalve to control board. 


They're in a 4 pin connector that plugs into the smartvalve. I'll snap a pic of it.


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## Angry Snail (Oct 8, 2013)

Here's the 4 pin connector - it goes into the smartvalve. The white and black wires with dashes go to the inducer motor. The plain black and white wires run down to a 4 pin connector at the board. Those 2 wires have 118v running thru them. The white and black wires with dashes, that go to the inducer - never have power.


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## beenthere (Oct 11, 2008)

Board in vale may have burnt out.


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## Angry Snail (Oct 8, 2013)

That's what i'm trying to figure out, what is bad. I don't have a ton of coin to just throw parts at this thing, would rather do a good job of diagnosing the issue and fix it than to just throw parts at it hoping something works.


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## beenthere (Oct 11, 2008)

Make sure all other molex plugs are in tight/properly. If it still won't send voltage to the inducer, its the valve. You can often see the damage on the board if you open up the valve.


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## Angry Snail (Oct 8, 2013)

Thanks, i'm reading the manual on the control board now. I probably should double check some readings just to be positive that i'm actually getting a call for heat. I'll have to read back thru this thread to figure out how to measure that, i've done so much checking that i've forgotten it already


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## yuri (Nov 29, 2008)

Basically the tstat sends a signal to the fan timer board which energizes a relay in the gas valve to turn on the inducer which closes the pressure switch then tells the smartvalve to light the pilot. pilot proves and sends a signal to the fan timer board to start the timer and then turn on the fan. have not seen one lately to tell you more. there may be some troubleshooting info at that Honeywell link I gave you. not easy to troubleshoot as the board talks to the valve and is interlocked. that board may be cooked as all the dust causes it to overheat ( boards hate dust ) and from vibration from the fan. some of the resistors/diodes or whatever they are look brown and overheated 2 me. fortunately HWell abandoned that system.


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## ben's plumbing (Oct 6, 2011)

you have to know for sure about checking for power at the proper points to be sure if it the fan timer board or the valve itself....there is enough information here for you to do that follow the chart on post 35...ben sr


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## Angry Snail (Oct 8, 2013)

Thanks guys, been busy with this thing. Tore it apart and cleaned the board just so it's easier to work with. 

I'm using a troubleshooting guide from Honeywells site. 

The big question I have involves dealing with electricity, I am not a fan of this stuff. 

The guide wants me to measure voltage across terminals (24 vac between transformer secondary terminals) I know where they are, do they want me to probe them with the wires attached or unplug them and measure the actual terminal on the board? 

They want the same check between Heat and Neutral terminals - all of them? Same thing, leave them plugged in or unplugged and check the terminal itself? 

This troubleshooting guide and all your help has me really close I think.


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## Angry Snail (Oct 8, 2013)

Checked voltage from transformer - 27 volts

Voltage between Heat and Neutral ( I used an unused neutral and another one that was being used) = 0 Volts


Says to replace the St9160


I think i've exhausted the diagnostics, order a part and see if I did it right


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## Angry Snail (Oct 8, 2013)

Wanted to stop in and say thank you once again for everyone's help!

New control board came in yesterday, I got it installed and voila - HEAT!!!!



I could not have done this without the help from members of this community - it just started snowing here so you guys really came thru for us.


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## davevalley (Nov 20, 2010)

*Concord Plus 80 Ignitor*

Hello experts,

I'm looking all over the web to purchase a flame sensor/spark ignition for a 1997 Concord HVAC unit. This part has three prongs. Two are for the ignitor and the other is the flame sensor, all in one.

Can someone please help me locate this ignitor....please. We're freezing.


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