Bryant troubleshooting help

[HayZee518]

Thermopile/Thermocouple

I drew this diagram of a thermopile - see if it makes sense

[chaka454]

Hope this helps

Hi guys I'm a service technician and your problems sounds very familiar unfortunately without checking the equipment I might not be of much help, but I guess anything helps right..... if the flame comes on and it shuts off after a short time like 10 or 20 seconds check the vent cap, it might be broken, check for an obstruction in the vent, if the cap is broken replace it, one good way of checking if its the vent is taking the cap off at the furnace and run the furnace but not for long you want to be smelling those fumes, this is to check if the flame stays on for longer than 20 seconds like somebody posted, one thing you never, ever want to do and I'm serious about this I've seen accidents happen because of this is to jump out safety switches specially the high limit switch dont ever jump those safetys, they save lives, hope this helps any questions i'll try to help if not I'll find out for you guys, we're a Bryant Diamond dealer so most of the equipment we sell, install, and service is Bryant.

[jubrand]

Possible solution and another Bryant problem

I have a Bryant plus 90 that's about 10 years old or so too. I've had some of the same problems you guys are talking about. Basically, the burner would fire and burn for about 10 seconds, then shut off. It would try 2 more times before it gave up and locked out for 3 hours.

We originally thought it was the flame sensor, then the gas pressure. None of that seemed to work. FINALLY, the tech (oh sorry, the THIRD different tech), realized that the wiring harness that connects the flame sensor and other burner components (sorry for being basic, I don't know too much about the wiring) was faulty. He replaced the harness, and that fixed it. You might want to check it. In my case, it was just one wire that was pulling out.

Now on to my NEW problem.......For the last week, the furnace can't seem to get the temp up to the setting on the thermostat. the thermostat (Honeywell digital with four time zone settings...wake, leave, return, sleep) will call for heat, and the burner will fire up and burn as it should. But, after about 5 minutes or so, the burner shuts off (blower is always on), even if the proper temp hasn't been reached. The thermostat still looks like it's calling for heat (small flame icon is showing). Sometimes, the burner will fire again, but most of the time it stays off. If I cut the power to the furnace (by opening the front cover to trip the safety switch, or by just flipping the power switch on the side of the furnace), it seems to reset something and upon turning back on, it'll fire the burner again and repeat the same process.

I've got the LED error codes on mine, and it's giving me code 33 after the burner shuts off. That corresponds to "Limit or flame roll-out switch is open".

Does anyone have any ideas??? I'd like to figure it out myself and fix it rather than pouring more $$ into techs coming out. Could it be the thermostat that's broken instead of the furnace?

Any help is extremely appreciated.

[HayZee518]

connect a jumper across the thermostat and see if anything kicks in. if it does and shuts down after the jumper is removed then you found your culprit.

[whacker]

Hi, original poster here.

Just checking in to say, I've not made any progress since last posting, and winter in Michigan has turned mean!

I've been on some other forums regarding this, and the only suggestions have been to check and make sure the condensate water is draining properly, which if it wasn't would influence the speed of the draft inducer fan, which in turn would influence the operation of the pressure switch. I don't think this is it, but I'm still investigating. I'm still leaning toward changing out the gas valve, but I'd rather not just throw good money after bad.

Hay Zee, I haven't been able to find a way to scan my owner's manual schematic and sequence of operations. If I do you'll be the first to get it.

So in the meantime, I'm relying on a neighbor to come and check the premises daily whenever I have to be gone longer than a day!

[jubrand]

Hi, original poster here.

Just checking in to say, I've not made any progress since last posting, and winter in Michigan has turned mean!

I've been on some other forums regarding this, and the only suggestions have been to check and make sure the condensate water is draining properly, which if it wasn't would influence the speed of the draft inducer fan, which in turn would influence the operation of the pressure switch. I don't think this is it, but I'm still investigating. I'm still leaning toward changing out the gas valve, but I'd rather not just throw good money after bad.

Hay Zee, I haven't been able to find a way to scan my owner's manual schematic and sequence of operations. If I do you'll be the first to get it.

So in the meantime, I'm relying on a neighbor to come and check the premises daily whenever I have to be gone longer than a day!

Have them check the coils above the furnace. Ours were filthy and they were slowing down the airflow and causing the furnace to overheat and lock out. This also ended up blowing the pressure switch. We replaced the pressure switch and it still wasn't working, then we opened it up and cleaned those coils, and that did the trick. The furnace even sounds "healthier" now and it's working fine.

Just as another troubleshooting tip, our furnace is bigger than it needs to be according to the tech, and since we have 2 floors (one is a half basement) and the thermostat is upstairs, I keep the upstairs vents closed in the winter to try to equalize the temp differential. He suggested just opening them all up in case that was effecting the furnace by restricting the flow too much. We did that as well. Might want to try these things to see if it works. Good luck!

[xxgoaler]

I have a Bryant furnace and am a gas tech. this has happened to my furnace and found that the air intake takes in to much air occassionally and sucks the gas away from the ignitor to fast. I solved this problem by two widths of electrical tape around the disk before replacing. Or if the intake pipe is just outside the furnace put fingers across the intake pipe and start. When you find the proper amount of area that needs to be covered you can cover that portion of the pipe with electrical tape. I have been working on furnaces for five years now and have seen it happen about three times all Bryant furnaces usually 1 pipe systems. Hope that works for you.

[tomkiti]

Burners Not Lighting

I have a Byrant Plus 90 furnace (350MAV) from 1996. When starting, the burners would not always light on the first try. The inducer fan would turn on, the igniter would glow orange, the gas valve would turn on, but there would be no flame. Sometimes it would fail all 4 times and the furnace would lockout with a code 14.

Thanks to xxgoaler's tip above, I pulled off the air intake pipe and placed two strips of electrical tape over the opening (one wasn't enough). This reduced the air flow sufficiently and now the burners light on the first attempt like clockwork. Thanks xxgoaler!

[cannonball503]

Bryant troubleshooting help

The error code I'm getting is 3-1. Three short flashes and one long flash. Can anybody help? How do I reset this?

[paul52446m]

The error code I'm getting is 3-1. Three short flashes and one long flash. Can anybody help? How do I reset this?

Hi paul here. I don't have all these books so i can't look up your code errors.
If you have your book or theses code might be on the inside of the door panels
then you can tell me what it says and we can go from there. To reset just turn off power, wait 5 min. and turn power back on, then watch it and tell me what
happens so we can start trouble shooting. later paul

[GOLDBUG]

Heat Sensor

I'm getting near the end of my rope, but luckily I found this forum (and intend to explore others as time allows).

I've got an early '90s Bryant Plus 90, Model398AAZ06060AAKA. It worked flawlessly up until two years ago, when it started to intermittantly not start up, but let me explain. In the sequence of events, no one (myself or any furnace repair guy) has ever been able to witness for the sake of troubleshooting what exactly takes place (the nature of intermittant), but here is the outline:

The inducer motor/fan will start up in response to the thermostat, but it quits before the burner ever comes on. Whether or not the pilot light makes it on is anybody's guess. This apparently puts the electronics into a lockout mode. If you switch off the furnace, either with the main power switch (furnace mounted) or at the thermostat, then switch back on, it will come back and start over, this time successfully. The furnace will work normally for anywhere from 24 hours to two weeks, then will fail again, whereupon you can reset it with the power off/on routine and go from there, with the results being another undetermined length of normal service.

The service people who've work on this thing have kind of come to an impass, and I've educated myself on the sequence of operations, based on the manuals that came with the furnace, so I could do my own troubleshooting, as I have a background in electronics. Not that I have anything against service people, but it has simply become a matter of parts swapping, as they don't seem to have any broad history of this particular problem to go by (plus it's expensive!), so I've turned to the 'Net to see who might be able to help.

Let me also say that, along the same time this problem started to develop, a leak in the secondary heat exchanger was detected (water in the blower compartment and then on the floor -- never to any level that would immerse the electronics), and that was replaced recently.

The service techs started out checking the inducer intake for obstructions -- no problem there. Then they swapped out the ignitor/lockout module (ILO -- a logical choice as I've come to learn). But because the furnace never fails in the presence of anyone (could take weeks), they pack up and consider it solved, until we call again. Generally, if someone is home, we just switch off/on the furnace and keep the house warm. The ILO has been changed twice!

Then the following parts have all been replaced: The inducer motor relay board; the pressure switch; the inducer motor itself (which, when it didn't solve the problem, they swapped back out for the old one, fortunately for me); the thermostat itself; the pilot assembly; the blower control PC board. I also, on a hunch, decided recently to bypass (put a jumper on) the high-temp limit switch, thinking that this might have become degraded due to the water possibly being blown around in the blower compartment from the leaky exchanger. Nope. It still fails and must be reset with the off/on routine.

The only thing left I can think of is that there's a problem in the redundant gas valve, perhaps with the opening of the pilot gas flow, but that's why I'm here today, folks. Keep in mind, the inducer motor seems to shut off early in the sequence, before the burners are ever on (that's what I keep trying to assess, but I'm never there or paying close enough attention when it shuts off).

Does anyone have a clue what might be going on with this thing? I'm not inclined to have the gas valve replaced unless the evidence is strong (mucho dinero, you see). I know the problem must be electrical/electronic in nature, but practically every part has been replaced. Has anyone ever had a problem with the 115VAC/24VAC transformer becoming intermittant? Haven't replaced that part yet. Or any electrical connectors becoming corroded, perhaps just a ground connection? Things in both compartments actually look pretty clean.

Aren't there any diagnostic devices devised that can be connected up to this to more closely pinpoint the area of trouble? That would be a good electronics class project!

I need help, or I may have to get a new furnace, which the two local outfits that sell/service Bryant would love to provide! But really, this has got to be something so simple. Everything else works fine on it, and it's only 15 yrs. old or so. Just a baby, really. But the services techs can't apply themselves in this sort of a problem for any length (understandably), so I'm trying to find out the fix myself. HELP!

"I have the same furnace that you have. The flame sensor is the biggest problem with this furnace. I have replaced mine 4 times already. It sounds like you are having the same problem and need to replace the flame sensor to resolve. If you need any additional assistance, let me know."

[Scruffy]

Bryant 398BAZ - fires up, blower blows hot air for about 1-5 minutes then shuts off

After reading the previous posts I would like to try and clean the flame sensor but I cannot seem to locate it on my furnace, Bryant 398BAZ. The only documentation I can find never seems to show or even talk about the flame sensor. Can anyone show me a picture or diagram of where the flame sensor is located?

Additional information. I was watching while the furnace fired up and the blower started and then stopped after a few seconds, the error code was 32 (low pressure). I shut it down and restarted it and got error 31 (high pressure). I shut it down and restarted it and got error 32 again.

After I shut it off overnight it started up and ran fine. But, meddling me, I changed the thermostat to a higher temperature but in the meantime I went through a lower temperature so the unit shut off. Now I cannot get it going again.

[HayZee518]

flame sensor

the flame sensor and ignition spark gap are the same unit. one electrode is the flame sense.

[Scruffy]

Thank you.

the flame sensor and ignition spark gap are the same unit. one electrode is the flame sense.

Thank you. It is difficult finding any technical information on this unit because it is so old. Bryant's website says that model does not exist.

[HayZee518]

Bryant 398BAZ

please go to your browser window and type in BRYANT 398BAZ and hit enter.
Two pages of a class action lawsuit comes up so your model number is good.

Maybe you could obtain some kind of payment to settle a claim on your unit.

the site HVAC REPAIRS lists five types of flame sensor rods for BRYANT.

You said you are wondering where the flame sense is. look in the flame path for the pilot light. it should be sitting right in the flame's path.