Bryant plus 80 heat exchager is cracked, i'm looking for a replacement heat exchanger

You may have burnt out your heat exchanger big $$$$ to fix

You could also clean the flame sensor .Look for a black sort of box or it may be round should be near the combustion fan.

It depends....on if you are talking about a small blower in the front of the furnace or the indoor fan motor. If your furnace is an 80% effficiency rating or above it will have a 'combustion air' fan....that will be a small on in front of the furnace in the vestibule under the front cover. If you have that motor and that is the one you are asking about...then YES it has to be running prior to the furnace igniting the gas.

If you are talking about the indoor fan motor for circulating air into your ducts, then NO it does not have to be running in order for the furnace to ignite. But it WILL have to run to remove the heat from the heat exchanger after it ignites or it willl overheat and shut off on high limit.

drain stopped up or bad pan

Not a good idea.

A 13 code means the furnace cycled on limit more than three times consecutively and is in a lockout for 3 hours. A 14 is ignition lockout. An ignitor does not intermittently quit working. I'm the service mgr at our shop, and I know that particular furnace model has a service bulletin out on bad secondary heat exchangers. If your lucky the filter is dirty, or the furnace condensate trap or drain is clogged. Most likely the secondary heat exchanger is plugged up and isn't allowing the pressure switch to make. Or the furnace is overheating due to it not being able to properly vent hot gas. Which would explain the high limit lockouts. Call an authorized carrier dealer so you can take advantage of the free heat exchangers and the $300 labor credit. You can also call an authorized Bryant dealer to perform the work for you. Only an authorized dealer can rectify this problem because the Bryant corp requires testing and paperwork in order to get your free parts and labor credit.
Good luck.

I'm going to have to assume that your talking about your vehicle. If this is the case, it sounds like your heat exchager has a pin hole leak in it. Does the smoke smell sweet? If it does, you're smelling the antifreeze. You can add the aluminum or bronze powder leak sealer to the radiator as a temporary fix, but the heat exchanger should be replaced.

I suspect a bad fan relay or bad fan control. Maybe the longer the control or relay is in the on position the more chance of it sticking on.

The heat exchanger is a bear to change. depending on the age of the unit it might be more practical to replace the unit. However unless you trust this service tech I'd get a second opinion, because it is rare that a heat exchanger will crack, plus by law he or she should have shut the furnace down do to carbonminoxde. Especially rare in Coleman Evcon series units.