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So Ive 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 peak inside, and i didnt 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 didnt 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.

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?

Thanks.

Does your Carrier model have a model number? Are you licensed? Did you check the gas pressures to make sure it isn't over-firing? Is there an a/c coil in the plenum? static pressure are good? Since you said rollout switch, I'm assuming you had to reset it manually?

Run a complete combustion analysis; with the blower fan on and fan off. The secondary heat exchanger could be plugged, ventor motor gasket damaged sucking air. The roll out is tripping for a reason,don't play games, sounds like its time to upgrade. Throw away world, 14 years old is no different then 30 years old.

you have a plugged secondary heat exchanger, you can replace it or replace the whole furnace.

go smell that vent outside while its running I guarantee it smells like formaldehyde's, and if you stick a CO meter in there its producing over 2000PPM.

secondary heat exchanger for sure