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Old 12-26-2006, 05:51 PM   #1
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Newer Lennox Elite Series Furnace Issues - HELP.


Hello Fellow DIY'ers.


I am having a problem with my Lennox Furnace. It works fine most of the time but every now and then it won't run when the thermostat tells it to. Turning the power off to the furnace for a second or two then back on again makes it run every time.

I've tried looking at the 2 diagnostic lights after a failure to fire up and it usually indicates a couple of items to check (of which I have no idea what I'm looking for - but am VERY handy and quick learner)

Indicator symptom 1: slow flash - both LED's - alternating
Indicator symptom 2: left LED (OFF) - slow flash right LED

As is typical unit has just finished warranty coverage.
Can anyone please advise on how to track down and resolve this issue. Where I should even begin to start ?

Unit is M/N: 90UGFA3-75-6
LENNOX ELITE SERIES (approx 4 yrs old).



Your wisdom is greatly appreciated - as soon as possilble.
Thanks
Deo.


Last edited by WyleeCoyote; 12-26-2006 at 06:01 PM.
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Old 12-26-2006, 07:16 PM   #2
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Newer Lennox Elite Series Furnace Issues - HELP.


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Last edited by acefurnacefixer; 12-27-2006 at 06:15 AM.
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Old 12-26-2006, 07:45 PM   #3
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Hello Ace,

Thanks for the RTFM advice. Have looked at the diagnostic sheet on pasted to the front of the unit - my issue is not sure what the varying parts it's asking me to troubleshoot are. (The Manual doesn't quite detail this out).

As this is a DIY post and you seem to be quite wise was looking to your vast years of wisdom for advice - not condemnation.

The units was serviced late last year due to a leak in one of the vent pipes causing CO2 to leak into my home with my young family in it. The unit was installed by a professional contractor who services all the homes in our area. when this new home was built (not fly by night as you are assuming) and nor did a get a "great deal" on it.

From your previous posts I thought you would have been a great resource to have help guide the rest of us not in the business to alleviate the costs of these high price "check-ups" - if your advice is to simply call and have it serviced then that's all you had to say.

Thanks anyway.
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Old 12-26-2006, 09:30 PM   #4
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Newer Lennox Elite Series Furnace Issues - HELP.


Hi WyleeCoyote

We are a Lennox as well as a Carrier dealer. The first code you gave was a low voltage or ignitor failure. Now you are getting ready to find out why me and my techs hate Lennox furnaces. There is a 9 pin square moldex plug on the board of this furnace. This plug has the limit and hot surface ignitor circuits in it. Sometimes you can pull this plug off and blow all the crud out of it and get it to work again. Most of the time Lennox furnaces of this vintage came out of the factory with one if not more of the wires not seated in the plug. The first thing I would like for you to do is to shut the power off to the furnace. Locate the 9 pin plug, push all wires one at a time towards the board into the plug. You will probably find that one of them is not seated. If you find one not seated you have fixed your problem. At this point you can plug your furnace back in and see if it runs ok. If they are all seated, chances are your sure light board has a loose socket on the 9 pin connector. Hope this helps.

Good luck
Rusty
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Old 12-27-2006, 06:21 AM   #5
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Newer Lennox Elite Series Furnace Issues - HELP.


Quote:
Originally Posted by WyleeCoyote View Post
Hello Ace,

Thanks for the RTFM advice. Have looked at the diagnostic sheet on pasted to the front of the unit - my issue is not sure what the varying parts it's asking me to troubleshoot are. (The Manual doesn't quite detail this out).

As this is a DIY post and you seem to be quite wise was looking to your vast years of wisdom for advice - not condemnation.

The units was serviced late last year due to a leak in one of the vent pipes causing CO2 to leak into my home with my young family in it. The unit was installed by a professional contractor who services all the homes in our area. when this new home was built (not fly by night as you are assuming) and nor did a get a "great deal" on it.

From your previous posts I thought you would have been a great resource to have help guide the rest of us not in the business to alleviate the costs of these high price "check-ups" - if your advice is to simply call and have it serviced then that's all you had to say.

Thanks anyway.
Lennox units are among some of the best made anywere...there quality control is unmatched by any other manufacture. The fact is that all furnaces made in this era break down, if its that close to the "warrenty date" Lennox will strech the dates to accomadate you, or even the installing contractor may do it. I am a lennox dealer.....i sell and install nothing but the best.
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Old 12-27-2006, 10:41 AM   #6
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Newer Lennox Elite Series Furnace Issues - HELP.


Hello Ace/Carrierman - thank you both for your replies.

Carrierman - did as you suggested and reseat the molex plug located on the SureStart board. Even took 1 step further and reseat ALL wires inside the furnace 1 at a time without resolving the issue.

Of note - the plug you mentioned oddly enough did not have a wire in location #9 (as labelled on the plug). Wire locations and colors as follows:

Pin#1 - Blue
Pin#2 - Yellow
Pin#3 - Brown
Pin#4 - Orange
Pin#5 - Purple
Pin#6 - Blue
Pin#8 - Brown

Not sure if this is a standards thing or not as this is a Canadian furnace just wanted to ensure you had all the info.

SureStart board is a White Rogers (50A62-121-06). Of note from time to time the furnace does actually kick in but is intermittent and cycles for approx 5 min at at time. Thermostat is brand new Honeywell programmable (set on HOLD pattern for now) to 23.5 Celsius and operational as it is sending signal to unit - as noted.

Seems like now there is no ignition on the burners - it tries 3 times then goes into WatchGuard mode. Tried to reset w/ power switch but furnace not firing up. When it does fire up and work the status light go into the alternating slow flash. (Runs for approx 5 imin) What is our next step?

Last edited by WyleeCoyote; 12-27-2006 at 11:02 AM.
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Old 12-27-2006, 10:54 AM   #7
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Newer Lennox Elite Series Furnace Issues - HELP.


Can you ohm out the ignitor?
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Old 12-27-2006, 11:19 AM   #8
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Newer Lennox Elite Series Furnace Issues - HELP.


Hi WyleeCoyote

It sounds like the molex plug on the board has a loose pin. The only way to repair it is to replace the board. The replacement board is 97L48 if you decide to replace it. Some of the Sure Lights had a five year warranty on them. Check with your local dealer and they can let you know.

Good luck
Rusty
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Old 12-27-2006, 11:35 AM   #9
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Hello Ace,

With your assistance I'm willing to try. Assuming you mean test the resistance across the ignitor - Sorry for my ignorance but assuming the ignitor in this system is located behind the shiny box where the burners are - what wires to do I test ?

Here is pic of furnace setup that will help me. If you could tell me where to to check that would be great. Thanks.
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Newer Lennox Elite Series Furnace Issues - HELP.-furnace-001.jpg  
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Old 12-27-2006, 12:22 PM   #10
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Hello Ace/Carrierman,

Further digging found that there is water in the system cauing the unit not to fire up. Tried draining some water out of the pipe that comes in to the fan - but when the blower initially fires up you can hear water in the motor area. There is a blockage somewhere and I need to find 1) blockage toclear it up 2) Get all the water out of the motor area (black turbine thing in the top section of furnace)

Also - as followup Carrierman- you were correct - the board does have a 5 yr replacement. The 3rd/4th digit of the s/n of the unit indicate the manufacture date (in my case 01) home bought May 01. Alas all was not lost - Got on the line with a great Tech that was willing to help troubleshoot with me on phone leading me upto "drain" issues and further isolate/negate listing of code symptoms on unit.

You guys have been great! Keep up the great help.

Last edited by WyleeCoyote; 12-27-2006 at 01:31 PM.
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Old 12-27-2006, 12:37 PM   #11
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Newer Lennox Elite Series Furnace Issues - HELP.


Can I call you ? My dime.......just post the number.Or send me a private message.
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Old 12-27-2006, 01:34 PM   #12
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Hello Ace/Carrierman,

Just quickupdate. Drained most of water out of system and functioning without shutting down. Temp now being maintained. My next steps will be to remove/drain inducer moter and clean all condensing lines and orafaces to ensure smooth operation.

I cannot explain the great feeling it is getting the right help in such a timely manner as you've been generous enough to offer.

Will keep you in the loop once we've given her the final once over.

If you think of anything else I should look for pls feel free to advise.
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Old 12-27-2006, 04:39 PM   #13
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Newer Lennox Elite Series Furnace Issues - HELP.


Hi WyleeCoyote

Just wanted to say excellent, glad you were able to get furnace going. I had not thought of going that way yet. That was my next step though.

Good luck
Rusty
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Old 12-28-2006, 03:14 PM   #14
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Wylee,
I am having the same problem in my lennox furnace and was wondering what steps you took to get the blockage cleared up?

-Shawn
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Old 02-28-2007, 10:09 PM   #15
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Hello ibwahooka,

Once the cover of the furnace was off found a black plastic hose (approx 1" in diameter) - followed the hose upto either end and just pulled it off and extended it vertically away from all electrical and emptied it into a pail. Repeated this for BOTH ends.

Of note - if you hear a "gurgling" sound when blower first fires up you may need to also remove the blower fan (approx 4 screws) assembly and just hold it upside down to drain water from it also.

To this day - all is good to go and am very happy guy thanks to the help from some super guys in this thread. Best of luck!

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