Ignition Proving Failure - Bryant 383KAV042091 AGJA, series G 88BTU/HR, 80% AFUE
Ran fine all last season. Power stayed on through the summer with thermostat on lowest setting. When turned on this season - no heat.
I would very much appreciate help with diagnosing this problem. I have read a bunch of similar posts already. It seems to be quite a common problem. I have replaced the flame sensor, which helped none, and the power company man measured the gas pressure just before the furnace gas valve( but not after). Said it was plenty, but I do not know what it was. Everything looks dry (control board) and clean, all ground connections check solid. I have not measured the voltage produced by the flame sensor when engulfed in flame. The flue is clear.
This is what happens:
Gas is on, power on, turn up thermostat to call for heat. The blower comes on for about 90 secs while code 12 flashes, as it should.
Blower goes off and the inducer fan comes on while continuous code led is on, as it should.
About 15 seconds later the ignater heats up, the valve unit gives a loud klick and all four flames come on for 2-5 secs.( the duration varies during different attempts . )
After the ignition fails the 1st time, the inducer stays on and led code changes to 34. There may be 2 more attempts to relight, but other times only one more. The 34 code stays on through these attempts. Finally the inducer goes off and the blower comes on. At this point the led may change to rapid flash( reversed polarity) and after a while go to 12 and then to 90 secs of blower and back to ignition attempts, OR other times these 2 particular codes keep "fighting " it out for a while until one prevails, OR directly to 12 and blower and re-ignitions, OR stay on rapid flash (polarity problem) for a long while and sometime it cycles like that and finally it locks at code 13 and stops. Then it takes much less than 3 hrs to reset itself and start over.
The flames are sometimes steady and other times they are pulsing strongly, more than flutter, i.e. they sort of come on from right to left in sequence or together they come on and almost ( or completely?) off 3-4 times very rapidly during the few seconds they are on before shutting down. They do this more often than a few days ago when I started playing with this.
I have alternate heat source, but it produces lot of moisture in the house.
Could I have a bit of advice, please, anyone?

Just because you replaced the flame sensor does not mean it is clean. Use fine sandpaper or steel wool and give it a good cleaning. Then recycle the main power and try to fire it over again. Post results. Everything has to be step by step and many people have replaced the flame sensor and did not replace the flame sensor wire back to the board. The flame sensor wire can also be a problem and is sometimes replaced or the ends cut off and new connectors put in place. Post results from the cleaning.

The next step after this will be to measure the flame sensor output.

Thank you hvac1000 --
Cleaning and firing done as per instruction - negative result. Both ends of the sensor wire are attached firmly on clean terminals.

OUCH well now it is probably going to get more expensive since cleaning the flame sensor was the cheap cure.

You still need to test the flame sensor output to be sure it is up to standards. Now we know it is clean but we do not know how well it is really working.

Yes, well... And how exactly would I proceed? What to connect to where? That is, am I measuring amperage? I have to go and buy an amp meter just for this.

Sorry, never mind about the above, I just saw the attachment th measuring instruction. Thank you, will post when done.

It has been weeks, sorry. So if this thread can be resurrected, I will appreciate it. Had a service man come in and analyze the problem. He checked "everything" and could not determine the fault and unconvinced he said to replace the control board, offered it for $200 + his %age. I thanked him, paid him $110 for 1.5 hrs of his time and said good bye. Now I am back to it myself again.
The flame sensor microamperage is as follows: when the flames come on, there is a surge apto 5, then it goes down to sttle at about 2.7 and then it goes up again to 4.5-5 just before flames go out. This was measured with an in-series connection with the meter's blac terminal on the sensor contact and the red to the sensor's wire connect.
All ground connections have been confirmed positive.

OK the next step is to check the gas pressure after the gas valve inlet. In other words we want to see if the pressure is correct going out of the gas valve to the burners and within the stated pressure as listed on the furnace tag attached to the furnace.

You mentioned in your post about flame pulsing so this is the reason for the test. A improperly adjusted gas valve allowing too much pressure will cause problems.

Thank you hvac1000 for picking up on this again. I will do as you suggest, but it will not be right away - I have to construct manometer and purchase necessary fittings to perform this test, so bear with me please. ( is there a "best" way to do this?) By the way, the pressure switch checks out OK.

Best way?

First off after you build your manometer send it out to a testing agency for certification or we will not know if it is accurate.

The easiest way to test is with a store bought or borrowed manometer.

I am taking this in progression of testing that I would use which is testing the parts or making needed adjustments then progressing to replacing parts if necessary. But having to build your own manometer is a new one on me. LOL

The manometer has to be accurate or it can throw off the entire testing phase. Go borrow a know good one to make it simple on yourself. OR sometimes Ebay has them cheap.

Water Manometer - eBay (item 300394830141 end time Feb-12-10 12:29:52 PST) (http://cgi.ebay.com/Water-Manometer_W0QQitemZ300394830141QQcmdZViewItemQQptZ LH_DefaultDomain_0?hash=item45f0ed593d)

The above is just an example

I meant U tube with a scaled water column. By "best" I meant where on the valve or along the manifold to attach the test tube. My guess would be to unscrew one of the spuds and attach the tube there.

I meant build a U tube with scaled water column. By "best" I meant where to attach the tube along the manifold (or past the valve). My gues is to pull one of the spuds (orifices) and attach it there with appropriate fitting. Or?

There is a fitting on the gas valve for this purpose. DO NOT use a burner manifold orifice. Truthfully I believe you are in over your head. LOL

LOL? I do not see any such marking on the gas valve. Is LOL some kind of HVAC term?
All that the Urban Dictionary gives me under LOL is:
1) "I have nothing worthwhile to contribute to this conversation."
2) "I'm too lazy to read what you just wrote so I'm typing something useless in hopes that you'll think I'm still paying attention."
3) "Your statement lacks even the vaguest trace of humor but I'll pretend I'm amused."
4) "This is a pointless acronym I'm sticking in my sentence just because it's become so engraved into my mind that when chatting, I MUST use the meaningless sentence-filler 'lol.
Certainly, you do not mean to imply that? I have now measured the manifold pressure as I described, but now am not sure about continuing here.

LOL? I do not see any such marking on the gas valve. Is LOL some kind of HVAC term?
All that the Urban Dictionary gives me under LOL is:
1) "I have nothing worthwhile to contribute to this conversation."
2) "I'm too lazy to read what you just wrote so I'm typing something useless in hopes that you'll think I'm still paying attention."
3) "Your statement lacks even the vaguest trace of humor but I'll pretend I'm amused."
4) "This is a pointless acronym I'm sticking in my sentence just because it's become so engraved into my mind that when chatting, I MUST use the meaningless sentence-filler 'lol.
Certainly, you do not mean to imply that? I have now measured the manifold pressure as I described, but now am not sure about continuing here.



Laughing Out Loud that is what LOL stands for in my book. That was in reference to the fact that you were going to build your own manometer and then you were going to hook it up to a burner orifice. That was the funniest thing I heard in a long time.

Sorry if I hurt your feelings.

I am here as a volunteer. I do not get paid or receive any other considerations for the work performed here so basically you are getting a free bee. It makes no difference to me if you want to continue or not since I have nothing to gain or loose no matter what your decision is but a good laugh once in a while is good for all.


I believe the bottom quote will sum up our final conversation.

People that pay for things never complain; It's the guy you give something to that you just can't please." - Will Rogers

Well then - I am glad to oblige you with a good laugh, since that is all you probably ever get aside from a "thank you". For more good laugh, including mine, observe this device that I built for a bit over $3 this morn: RV U Tube Manometer (http://www.rverscorner.com/manometer.html). I took out one of the 4 orifices ("spuds" as I am told) on extreme left, screwed in a close nipple of the same size and attached the vinyl tubing to it. Then I fired the furnace just long enough to measure the manifold pressure. I know of the valve's pressure out tap - I just wanted to farther down the line to make sure exactly what the orifices get. So again, let us laugh together now, 'cause I messed with the pressure adjustment till it was right at 3.5" WC on my gizmo That must have had some effect on something, because the furnace fires up and runs now.
Thank you for your time and help.