I have a lennox 1994, 80% ignition, furnace. I am having a problem getting the burner to stay on until the house reaches the specified temperature. When the burner shuts down, the blower keeps running. In order to get the burner to kick on again, I have to fool with the thermostat such as turning it down below the actual temperature in the house, wait a few minutes and turn it back up, at which point the burner will kick back on for a few minutes but then it will shut off again and I have to go thhrough the process all over again.
What is the problem? Please help.

Sounds like you are having a problem with your limit switch

How is your air filter?

Try leaving the thermostat turned up, now check at furnace to see if flame goes on and off, and back on(over and over again) over a period of say five to ten minutes. There are a few options for your problem, but I would start here first. Let us know what you find and we will try to help further.