Have a carrier furnace, draft inducer comes on, glow stick lites up, burner comes on then blower then the flame rollout switch trips 2 mins later. I checked with the company and it is a L250, ordered and replaced it, same thing. Blower runs fine, its a 2 or 3 stage furnace. Theres 4 wires from the thermostat.
Ive tried so many things,
return air grill
exhaust and air intake ( which by the way is pipe out the side of the house with a pipe in a pipe system) they are clear
Draft inducer runs high speed then when burner comes on goes to a low speed. ( is that normal)
It does feel like the top of the furnance is getting to hot, and when i pulled the blower motar out there was a wet spot in the back of the unit and none of the tubes were leaking, Ive checked all the tubes for leakaged and plugs, its on a pump which works fine, and its not cold here so nothing is freezing.
Im thinking the heat exchanger is crack and the water is coming from there, there is signs of water stains on the back of the unit going up. Please help
Your symptoms all point to a leak in the heat exchanger. A tech would use a sniffer to verify CO leakage before pulling it out. Keep screwing with it and you might burn your house down.