It could be 6 or more problems.
There is a end switch on the damper door and it may not be closing properly. You may also have a problem with the S86 ignition control or the BCC board.
Point is that is a very complicated unit for any DIYer to try fix. It is also very expensive to get fixed by a Pro as you may end up with multiple problems.
It also has a problem with the heat exchanger cracking on 95% of them. Not worth fixing IMO.
If you want to then call a experienced Lennox tech.
There is a end switch on the damper door and it may not be closing properly. You may also have a problem with the S86 ignition control or the BCC board.
Point is that is a very complicated unit for any DIYer to try fix. It is also very expensive to get fixed by a Pro as you may end up with multiple problems.
It also has a problem with the heat exchanger cracking on 95% of them. Not worth fixing IMO.
If you want to then call a experienced Lennox tech.