So I've been servicing my furnace. Its a carrier model, and it is almost 14 years old. Now my rollout switch is tripping. I checked my filter which is clean. I am worried that it can be a cracked heat exchanger. I opened the plenum a bit just to peek inside, and I didn't see any cracks. However, when the furnace runs, it gets extremely hot on top. I cleaned my burners and cleared the orifices, but I still have the same problem. I started the furnace, saw the flames shoot out, I looked at it before the blower kicks in and after. I didn't see any flames dance or shoot back after the blower kicks on. I also checked outside to see if my exhaust was plugged but it wasn't. I contacted the HVAC 24 hour emergency service and they came in made the situation under control. What can be the problem? Does anyone else have any tips that I can try? Should I check the amperage of my ventor motor or blower motor? Could that also be the cause of the problem?