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  1. #1
    Join Date
    Oct 2008
    Location
    Bellevue, WA
    Posts
    194

    Lennox G24M burned controller board

    I went over to look at my mom's furnace today to see if it had a "summer fan" switch. Her old one did but it was down in the crawl attached to the furnace. Access is through a closet floor hatch so it's not much harder than going down to a basement. Anyway, inspection showed they had net rewired a fan only switch or hooked it up to the tstat (dumb).

    The furnace is working fine but I noticed when I had the cover off (no cut off switch for the cover which I found strange) that the "new" controller board she had to have installed 2 years ago has black burn marks in the PCB and one of the components looks fried. The furnace is 10 years old. 8 years doesn't seem like a very long life for a part that's a third of the cost of the furnace and to be scorched after only two years seems really bad. Is this a common issue? The replacement instructions were left inside the access panel (also doesn't seem wise) and it looks like Lennox buys these boards from White Rogers.

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  2. #2
    Join Date
    Oct 2008
    Location
    Bellevue, WA
    Posts
    194
    Bump?

    Anybody seen a control board with burn marks like this that was still working? The red and green LEDs blink slowly which I read in the instructions indicates normal operation. I noticed that when power is applied there is a slight humming noise (like a transformer noise) all the time. I guess that makes sense because you have to convert the 110VAC to something like 5VDC to run the microprocessor and 24V (or something like that) to the tstat but it seemed kind of loud. We have low power fanless PCs at work that don't make as much noise as this controller board. Is this normal.

    When the house was built the power to the furnace was shut of by a switch in the closet (access to crawl space). Now there is another switch right at the furnace. I'm betting this was added to meet new codes. I told my mom when she's not using the furnace, which is several months out of the year to turn it off at the switch. Does that make sense to save energy and prolong the life of the controller board?

  3. #3
    Join Date
    Jun 2008
    Location
    Monroe Ga
    Posts
    77
    To answer your question about being "normal". Your answer is no. The "sure light" board is a very common control board. find a lennox dealer in your area and they should have one on the truck or at least in stock in their shop. Lennox had many furnaces that utilize that particular control.

  4. #4
    Join Date
    Jun 2007
    Posts
    24
    Yep. Look like you have an issue there. I would put the door back on and call a local Lennox dealer to check it and have it fixed before winter comes and Mom has to deal with an after hours call.

  5. #5
    Join Date
    Jan 2009
    Location
    Ypsi. Mi.
    Posts
    198
    call for service you need to have a lennox dealer come out and check it out.alot of part`s dealers won`t just sell you a part off there truck at least around here we won t.i`m not allowed to like most of us contractor`s. `

  6. #6
    Join Date
    Jun 2008
    Location
    Monroe Ga
    Posts
    77
    Quote Originally Posted by RLEE2344 View Post
    To answer your question about being "normal". Your answer is no. The "sure light" board is a very common control board. find a lennox dealer in your area and they should have one on the truck or at least in stock in their shop. Lennox had many furnaces that utilize that particular control.
    Wasnt saying to by one and install him self..Sorry if i was misleading. Call your local lennox dealer. One of their TECHS should have access to this part either on THEIR truck or in THEIR shop. But let THEM install it

  7. #7
    Join Date
    Oct 2008
    Location
    Bellevue, WA
    Posts
    194
    Can't mention the price but this board was just replaced two years ago. If the damn things going to eat boards that are a third of the cost of a new furnace it doesn't make sense to dump any more money into a ten year old furnace. Mom's actually thinking of a HP. Ideally the furnace should be replaced at the same time a HP is put in and she may go that route. I'd mentioned that the cheaper route would be to just add AC and continue with the furnace for heat but that was before I discovered this and it really doesn't make sense if the furnace has to be replaced anyway.

    Not impressed with Lennox. Is the first control board going bad after eight years about average? Any clue why this one might have issues at two years? That can't be normal which makes me start to wonder if there was something else wrong that should have been replaced at the time the controller was or if perhaps something was botched on the install. Saw in the instructions the replacement had different jumpers to cover a range of incompatible systems. It wasn't rocket science but it wasn't a DIY job either. Very leary of throwing good money after bad at this point.

  8. #8
    Join Date
    Oct 2005
    Location
    sacramento calif.
    Posts
    1,187
    between what you know and what the lennox tech tells you thats going to be quite a story. sounds like a possible "temporary" repair. thats a great furnace, tell us how it goes.
    i was born under a wandrin star.

  9. #9
    Join Date
    Oct 2008
    Location
    Bellevue, WA
    Posts
    194
    I guess I need to make a call to the company that installed the replacement board (not the same one that installed the furnace). Doesn't cost anything to ask. The response might make them a strong contender for the HP or AC install... or it might make me think it was a bad choice to have ever had them out in the first place. I have no doubt there are people that would jack up the price or otherwise take advantage of a widow. For the record, I don't think the company that installed the board did that. Hunting around I think the price was expensive but fair. Those boards don't come cheap! But, it wouldn't be the first time someones botched a repair and covered it up. In searching the forums I found a similar issue where ignitors were being burned out by the installer using a board with the wrong voltage (baldloonie pick up on it right away) and only coming clean on it when the HO called them back with the knowledge of what they'd screwed up.
    Last edited by Alden_Sloe; 08-06-2009 at 02:53 AM. Reason: typo

  10. #10
    Join Date
    Jan 2009
    Location
    Ypsi. Mi.
    Posts
    198
    That is a good furnace but I work for a lennox dealer.I do have to say I have installed a lot of those control board`s on that furnace.Dont know why it seems some of them eat up the board.

  11. #11
    Join Date
    Sep 2002
    Location
    Northeast Ohio
    Posts
    4,842
    Is the crawl space damp? How is the electrical power in the structure, any problems, lights flickering, short bulb life that type of thing? Besides blaming the failure on the control, have the service tech look for other answers that can cause this type of failure.
    A good HVAC tech knows how, an educated HVAC tech knows why!

    DEM


  12. #12
    Join Date
    Oct 2005
    Location
    sacramento calif.
    Posts
    1,187
    Quote Originally Posted by Alden_Sloe View Post
    I guess I need to make a call to the company that installed the replacement board (not the same one that installed the furnace). Doesn't cost anything to ask. The response might make them a strong contender for the HP or AC install... or it might make me think it was a bad choice to have ever had them out in the first place. I have no doubt there are people that would jack up the price or otherwise take advantage of a widow. For the record, I don't think the company that installed the board did that. Hunting around I think the price was expensive but fair. Those boards don't come cheap! But, it wouldn't be the first time someones botched a repair and covered it up. In searching the forums I found a similar issue where ignitors were being burned out by the installer using a board with the wrong voltage (baldloonie pick up on it right away) and only coming clean on it when the HO called them back with the knowledge of what they'd screwed up.
    for "the record" i do.
    i was born under a wandrin star.

  13. #13
    Join Date
    Oct 2008
    Location
    Bellevue, WA
    Posts
    194
    Quote Originally Posted by heaterman View Post
    Is the crawl space damp? How is the electrical power in the structure, any problems, lights flickering, short bulb life that type of thing? Besides blaming the failure on the control, have the service tech look for other answers that can cause this type of failure.
    Power is rock solid. When my folks built the house they ran 12 AWG copper wiring everywhere instead of 14 AWG. The crawl is bone dry. Never a hint of condensation down there. Never had any problems with other electronics in the house and the furnace is on it's own breaker. Probably wasn't much "electronics" in the original furnace but it lasted almost 30 years. The rest of the furnace is like new but eight years on an expensive component like the controller and needing attention again two years later I can't see repairing again unless there's a cause that can be addressed to have some faith that it's not going to reoccur. Unfortunately there's no way to know how long the board has been in this condition (could have been from the day it was installed) or if the first board failed in the same way.

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