This guy, skipp025atyahoo , has some excellent info...here's a small snippet of his postings:
Blowers that don't shut off.
Blower speed control is handled by the small micro controller board. A test might be the
blower being combustion or distribution is running at any speed is indicated by the LED
(lights) on the controller. Related to the problem of a blower running even with the stove
off or cold, is the LED indicator for that blower lighted (on)?
The sad part of the above problem, is how a blower constant run problem is probably tied
to a micro controller board electronic part. It's beyond the scope of this post to try and tell
you how to service the board, while it is possible and in many cases relatively easy for the
proper electronics person to service... finding that proper and reasonable electronics
person (with the available time and an honest pulse) is not easy. It might be more cost,
time effective and truly easier to just replace the micro controller board.
If the LED and blower remain on with a cold stove, the micro controller is probably still in
a run condition. This is quite different from the blower remaining on with the LED off, often
indicating a specific controller board part(s) problem.
The blower and LED on, controller possibly still in a run condition is probably related to one
of two choices. First is a bad ESP, which is the cheapest first replacement choice. Second is
a glitch or old firmware within the micro controller firmware or the board itself. Replacing the
micro controller (computer) board is about a $200 cost (as of late Dec 2014).
https://www.hearth.com/talk/threads...ing-help-and-information.137772/#post-2147281
Blowers that don't shut off.
Blower speed control is handled by the small micro controller board. A test might be the
blower being combustion or distribution is running at any speed is indicated by the LED
(lights) on the controller. Related to the problem of a blower running even with the stove
off or cold, is the LED indicator for that blower lighted (on)?
The sad part of the above problem, is how a blower constant run problem is probably tied
to a micro controller board electronic part. It's beyond the scope of this post to try and tell
you how to service the board, while it is possible and in many cases relatively easy for the
proper electronics person to service... finding that proper and reasonable electronics
person (with the available time and an honest pulse) is not easy. It might be more cost,
time effective and truly easier to just replace the micro controller board.
If the LED and blower remain on with a cold stove, the micro controller is probably still in
a run condition. This is quite different from the blower remaining on with the LED off, often
indicating a specific controller board part(s) problem.
The blower and LED on, controller possibly still in a run condition is probably related to one
of two choices. First is a bad ESP, which is the cheapest first replacement choice. Second is
a glitch or old firmware within the micro controller firmware or the board itself. Replacing the
micro controller (computer) board is about a $200 cost (as of late Dec 2014).
https://www.hearth.com/talk/threads...ing-help-and-information.137772/#post-2147281