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Discussion Starter #1 (Edited)
Hi,

Our 1999 Lennox 80UHG furnace has been failing to ignite on an intermittent basis. It's been every 1-3 weeks that it happens. Most of the time the ignitor is failing to come on. Each time I am able to "fix" it by removing and reconnecting the wire that connects to what I think is the flame sensor (the one on the opposite end from the ignitor). Each time the LED diagnostic light were both flashing quickly, indicating normal operation.


This morning, the furnace was failing to come on and when I looked at the LED's they were: Top light-on, Bottom-slow flash. By the guide on the panel, that indicates an "Open Roll-Out Switch Circuit". This is the 1st time I've seen this code. I was able to do what I've done in the past-Remove/re-connect the flame sensor wire- and the furnace seems to be working fine again.

Any suggestions as to what might actually be happening? I'm wondering if the control board is bad? I say this because it happened once the day after the furnace tech had come to inspect the system. He came back but couldn't find anything and indicated it might be the control board, which they would replace for $600 or so. Obviously, I'd like to fix it if I can for less than that if I can.

Any help will definitely be appreciated!
 

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The flame sensor is not in the same circuit as the rollout switch. Disconnecting it should not reset your furnace. Sounds like a control board issue.
 

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Discussion Starter #3
The flame sensor is not in the same circuit as the rollout switch. Disconnecting it should not reset your furnace. Sounds like a control board issue.
Thanks for the info. Now, if it's a control board, are there reliable replacements that I can get that are reasonably priced? The HVAC tech quoted around $600 to replace the board. I'm not a service tech but I can follow directions, is this something I can do safely for less?
 

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