Flame on... Blower does not kick on
Lennox G24M3 Furnace
Original Board was Surelight 63K8901
Replacement Board is 83M00
First of all, I'm not sure what/if this qualifies as a DIY issue, so I'll post hoping some kind soul can help me figure this mystery out.
Originally, the problem was that the furnace (natural gas with no cooling hookup) would kick on when the t stat was calling for heating in the following sequence:
1) Purge motor turns on
2) Ignitor lights flames
3) Flames turn off after several seconds
4) Repeat step 1
The blower motor would never turned on and the flames would turn off (presumably on high limit). I tested all the limits, and they tested OK. This includes the primary limit in the heat exchanger, two rollout switches at the venturi, and the combustion air prove switch at the purge motor.
The blower motor worked fine when the t-stat fan control was manually switched to on. In addition the fan works fine when jumpered (all three speeds work), and the furnace would operate normally with a jumpered blower motor (of course with the exception that the blower was running 24/7). Therefore I concluded that the board must be bad and I replaced the board.
Now the furnace is doing the exact same thing as before with the new board installed but with one exception. The jumpered blower still works in all three speeds, however the furnace kicks the flames off even with the blower operating (it did not do this with the original board).
I am at a loss as where to go from here... any help at all would be appreciated. Thank you in advance!
Here is the schematic for the furnace:
The DIYer pays twice. Call for service from a qualified pro before you tear something up or cause an unsafe situation.
It's something a pro should easily be able to handle. You should check the contractor map for someone near you.
I forgot to mention that I also tested the main pressure switch and it testd out fine as well....
Thanks in advance!
I guess the message didn't get thru well enough, so I'll say it again. No DIY advice. If you know the sequence of how things work then you'd know the problem and have it fixed. Since you're probably not a tech, you don't know these things and that's ok. That's why you need to call a pro. Gas furnaces are very dangerous, not only to you trying to work on it but your family also.
Just keep replacing parts... Eventually you will change the right one... If all home owners got on This website and asked for info on how to fix their furnace none of us would have a job.
As these guys have already pointed out, there's a no DIY rule here on this forum.
Sheesh.... message received everybody. Just out of curiosity, exactly what kind of questions do the pros help out with on the Ask Our Pros Owner Assistance Residential HVAC Forum anyway? A note to the Admin... I read the site rules before posting this question. Some wording in the site rules like "Please to not post with repair questions" would have been very helpful and saved us all a lot of wasted time. DIY is a very broad category and I was not sure how my question fit in to the whole spectrum. Now I know. Sorry to inconvenience you all.
BTW, if anybody cares, I resolved the problem. The new board was functioning fine as it should in operating the blower (this is where the old board failed). The additional problem was in the thermocoupler wire... there was a bad connection at the terminal. I may have caused this when it disconnected it from the previous board. In any case, it works now.
Love the guys who posted with their sage professional advice saying "call a pro" or "DIYers pay twice" or "if we answered your question we would be out of a job" or especially the guy who said "If you know how these things work you would have already had this fixed." Thanks for all your "help." What a nice and helpful community. Next time add some new wording in your site rules that specifically say you will not answer repair questions, and kindly offer those of us troubleshooting real problems to another forum where we can get some actual help.
Glad you got it fixed. We can't lead a homeowner in any type of electrical, refrigeration, or fuel troubleshooting. It is for liability, we don't know how mechanically inclined any of the folks posting in the aop area so it could get ugly fast with someone not understanding what we would try to convey. If you work in some type of mechanical field you could apply for pro membership and once approved you will get all the help you want from some really knowledgeable guys/gals.
Thank you J Trammel... Will do that. I am a general contractor now, but I did work for two years as a maintenance guy for a large school district. Most of my mechanical experience comes from heat pumps and boiler systems. I don't know if that counts for anything, but I'll give it a go. Thanks again!
Originally Posted by MartinTravels
Its already in the site rules.
1. Who Is Welcome Here?
Anyone in the HVAC/R related industry, home or building owners with HVAC/R concerns and other polite and fun people willing to contribute. Please feel free to ask any question relating to HVAC, or other topics of general interest except Do-It-Yourself (DIY)
. We welcome questions so please don't be critical of someone's question, or other member's answers.
a. All site users must treat other site users with respect. Anyone who posts defamatory, insulting or otherwise disrespectful comments toward others will find their posts deleted and possibly their posting privileges suspended or revoked.
b. Any site user that becomes belligerent, argumentative, posts smart-ass comments or requires too much attention of the Moderators will lose their posting privileges either with or without warning.
c. Any post or reply that we feel that may cause harm to others or violates any of the site rules will be edited or deleted.
HVAC Pros, please note; home owners are welcome to ask questions here, if you do not wish to be helpful that is fine but do not intimidate, obstruct or criticize those that wish to be more helpful than you. If you do not like a particular thread or topic, do not reply and please move on.
2. Do-It-Yourself (DIY) - not here
This site is for industry professionals and folks seeking HVAC/R advice and knowledge. Please do not ask for step by step instructions on purchasing, installing or repairing your own equipment. This is our job and our livelihood. We are generous, but not to a fault.
Questions of this type will not be answered and may be deleted at the discretion of the Moderators.
Its in the first 2 rules, but its easy for some to miss it.
keep this in mind with the no diy help here... YOU may be able to safely repair your system with a little guidance, however, others that will read your answers and apply it to their own situation may not be able! in the open forum, instructions/assistance of that type can get people killed, and it's not permitted here.
The TRUE highest cost system is the system not installed properly...
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Last edited by beenthere; 01-27-2013 at 07:22 AM.
Reason: Non Pro * Member