Anybody do HVAC work/help? Its a 80's Lennox gas furnace. On a call for heat: the pilot kicks on, ignites, LED on the ignition control is on so induction motor is pulling good vacuum, main burners kick on, but the main blower never kicks on.
I've done a fair amount of googling, I think its the fan limit switch. I can watch it take little jumps and it gets over 100, but after about 2 mins after the main burners started the limit switch jumps to 150 and everything shuts down... How smooth should the limit switch dial climb, and when should the main blower turn on?
Right now i just set it for heat and after it lights i turn the blower on manually to blow the hot air.
Ideas?