Lennox gas furnace G1205-137-3

[brad]

Have this Lennox gas furnance that is about 20 plus years old,it has been a very good furnance,but now the burners won't light.The pilot is on and burning,but when you call for heat with the thermostat the burners won't light.Checking the terminals on the gas control  at TH (yellow wire)  and TR  (brown wire) no power,I should have power here when calling for heat shouldn't I? All the panels are in place.Where do I go from here as far as troubleshooting?

[JWWebster]

Their should be a resetable klixon/limit near the gas valve. Look for conditions like rusted burners or blocked vent and correct that after resetting klixon/limit.

[brad]

Thanks for the reply and advice,I'll check it out.