Hi all,
Had a Goodman GDH8 installed not quite 2 years ago, last winter just 2 months out of warranty, it started acting up. From what I've read, a somewhat typical issue where the ignition system starts, glows all nice and red, then with a click and a hiss, attempts to light the burner, and it it fails to light, will try 2 more times before going into a system lockout with a single flashing light. I turn the furnace off, wait several minutes, turn it back on, and hope it lights this time. Sometimes, it actually does light on the 1st, 2nd, or 3rd attempt and we have heat.

Called the company that installed it and they sent a tech out. (Who much preferred standing in my living room talking to fixing the furnace.) He checked all kinds of things over a period of ~3~ visits, and found nothing. On his third visit, my husband had gone online and did some research and told the guy to check the ground. He did, and found that the guy that had installed the furnace ran the ground incorrectly. He corrected the problem. So, several hours and a $330.00 bill later on an almost new furnace, we thought we had finally had a furnace that worked. It ran fine for about a month then right before Spring arrived and we stopped using it, it started all over again. I was so mad I just shut the dang thing off.


Same thing now, turn it on, it cycles through 3 ignition attempts, then locks out with a single flashing light. But only sometimes. (Except for tonight, where I can't get it to light.) Called a different company altogether and the tech, (recommended by a couple friends), came out today and said it sounded like it wasn't getting gas. He checked all that, and apparently, gas flow is fine. So after a time, he came and said he had found a small dark spot on the back of the circuit board. He said "it isn't burned all the way through". (Yikes?) He is bringing a new circuit board back tomorrow to try. (Ka-ching.)

Frankly, we do not have the money to spend on another 2 or 3 or 4 visits. If the circuit board isn't the issue, what should I do? My dad was in HVAC for many years; I know these guys are highly trained and work hard. But obviously, they don't know these Goodman furnaces and all the little quirks I've read about. (The main problem being that Goodman doesn't train their techs enough, from what I've read after hours and hours of researching these furnaces online.)

Can I ask the tech to re-check the ground, or check the igniter for tiny cracks, or the limiter switch on the blower, or the high limit switches? (This is if the board isn't the issue.) Or should I just keep my mouth shut? I have to tell you, I'm really cold because I still cannot get the furnace to light tonight and I'm very very frustrated with this on-going situation.

The unit is only 2 yrs old? Should be under wanrrenty for at least 5. sounds like the ignitor needs bent into the flame a little more.

That's what I thought also, Josh. But when I checked the warranty, it said a year for parts a labor.

I can only hope it is a simple fix, think the tech will be offended if I tell him that?

And thanks!

The only thing that can stop a furnace from lighting, if the ignitor is glowing and the gas valve is working would be.

Bad ignitor placement
Low gas pressure
Dirty burner orifice, not the case if it lights most of the time.
And bad sequence timing on the control board.

I have never seen a furnace without a 5 yr part warranty!

w
http://www.goodmanmfg.com/Home/Products/GasFurnacesStandardEfficiency80AFUE/MultipostionDualaverConvertibleGMH8GDH8/tabid/234/Default.aspx

Perhaps the orifice facing the burner closest to the ignitor is partially clogged. I have detected this situation before by using a stick lighter to establish ignition, and found that all but one burner was lighting - naturally, the one closest to the ignitor.

Hmmm... so if it is the circuit board, I will definitely be getting a hold of Goodman!

I'll mention these things to the tech when he returns tomorrow; I just wish I could the dang thing to light tonight. We live in a concrete block, cement slab, big open roomed, 1 story building and it is really cold in here now. (It's my father-in-law's old TV shop he built in the 50's.)

What is happing tonight? Does the vent fan and the ignitor come on? Or is something different happing now??

Same thing. Igniter glows, it won't light, and shuts itself down after 3 tries.

Oh, and it was running when the tech left this evening.

Were you with him while he was looking at the furnace? Is the ignitor dimming before the gas starts to come in?

That I don't know; but I don't think it was dimming. I'll check it now...

I was near him, but not with him.

No it's not dimming, has a steady glow.

Is the ignitor flat or round? And can you see the barcket holding it?

Here is a bonus feature offered EXCLUSIVELY by Goodman: self-diagnostic confusion. I have encountered a few Goodman units that experienced a failure of the pressure switch, but the circuit board did not recognize it correctly. Initially, the P/S would engage, but faulty contacts could not support the progressive increase in current as the circuit board relays were being powered in sequence. Enough current was passing through the P/S to "fool" the circuit board, but not enough to sustain operating sequence. A timely by-pass of the P/S revealed the problem.

It's round, and I might be able to see the bracket if I (carefully) stick a mirror in there. Which I going to do right now...

Here is a bonus feature offered EXCLUSIVELY by Goodman: self-diagnostic confusion. I have encountered a few Goodman units that experienced a failure of the pressure switch, but the circuit board did not recognize it correctly. Initially, the P/S would engage, but faulty contacts could not support the progressive increase in current as the circuit board relays were being powered in sequence. Enough current was passing through the P/S to "fool" the circuit board, but not enough to sustain operating sequence. A timely by-pass of the P/S revealed the problem.


This is what could be happening, I had it do that once on a trane unit.

No bracket, it is held in place by a small collar/hole going through the metal above the burners.

Is this ignitor metal or ceramic? I hate these new metal ignitors. Find the presures switch? And the little tube that goes between it and the vent motor. Gently remove the tube and blow gently into the switch and the motor. Maybe this will take care of the question kc was having.

It's ceramic, I'll try and locate the pressure switch. Little round thingie, right? Lol

Yep with a little rubber tube going from it to the vent motor.

Ok, did that, turned it back on, and 1st cycle, nothing...

Dang. Didn't work.

Well that puts us back to gas pressure. Or the ignitor. But you say that it is one that goes threw the metal cabnet and can not be moved. And the control board timing. You could try to clean the burner orfice with a small wire on the burner closest to the ignitor.

Ok, I'll try and do that.

And Josh? I really appreciate your trying to help.

A small restriction inside the burner or orifice that set in front of the hot surface ignitor will keep the system from lighting.

Are the orifices inside the holes behind the ports? If so, I can't get to them as there is heavy wire mesh in the holes.

The orfice is the small brass plugs coming out of the main black gas line that sends gas down the metal tubes to the ignitor. They are on the gas manifold

The orifices are in the gas manifold that supplies fuel to the burners.

Ok found them. Gently poked a wire into them and turned the furnace back on. Waiting...

Nada... Guess I'd better get my electric blankets out.

Well the only other thing you could try, sense the tech is coming back tomorrow would be to turn up the gas pressure a bit. The tech thinks the probem is in the board?

I know he did check the gas; he said there is a small burnt spot on the back of the circuit board.

Well I guess you will just have to wait and see what he finds out. Let us know what it turns out being!

I will Josh, and thank you again!

Update: It wasn't the circuit board, and it's still not fixed. However it is back to firing sometimes again, so we do have sporadic heat. Daniel (the tech) adjusted the gas pressure up a bit, and is considering trying a new gas valve on it. However the valve does appear to be working...

The only thing he can find that is a bit off is the amount of air it takes in before it fires. (Or attempts to fire.) He says he hasn't seen one draw as hard as this one does before.

He is stumped, he says there is no reason that he can see that it isn't firing. (He also checked circuit board/pressure switch by bypassing the P/S as KC13 suggested, and that wasn't it either.) He says he will get to the bottom of it if he has to call Goodman to do so.

Go Daniel!

I'll update as we learn more.
Have a great weekend!

Glad you got some heat.

What did he set the gas pressure at?

Not sure, said he bumped it up a little. He is going to swing by tomorrow and bump it up a little more to see if he can keep the dang thing running.

Here is a Goodman factory service manual for your unit.
Your furnace trouble chart starts on page 28

If you have not cleaned the flame sensor do so. Use steel wool or sandpaper. Many times cleaning it will not take on the first try so clean it again to be sure.

If the light is blinking on a continuous basis then you have a case of polarity reversal. Reverse the 24 volt power leeds going to the board. This is a very common problem.

http://www.alpinehomeair.com/related/GME8,%20GMH8,%20GDH8,%20GMS8,%20GDS8,%20GHS8%20Ins tall%20Inst.%209.09.pdf

Thank you hvac10000.

Thank you hvac10000.Congratulations on the promotion, hvac10,000! After 2 1/2 years, I haven't even made it to KC14. :p

AWW it was nothing.

Oops lol

Oops lolWe all are. :D

Oh, forgot to say that Daniel returned this morning, bumped up the gas pressure a little more, and the furnace was been working fine since. (Knocking on wood here, hard! Lol)

He wants me to call him in the next day or so and let him know how it is doing; I'll try and remember to ask him what he set the pressure to.

I see lots of other Goodman furnaces doing the same thing ours was; I hope that this simple but hard-won solution works for them, too.

Thanks again, all!

Just got off the phone with Daniel, he said to tell you all that he set the pressure to 3.5 in the water column (w/c).
I hope this helps someone else!

And again, thank you all for your time and efforts to help me solve this. You guys are The Bomb!
mrsmoondog

3.5 wc is a standard setting for natural gas. Hope your problem is solved.