Cracked heat exchanger?

Hey guys, a fellow real estate agent called me yesterday inquiring about a home inspection report that the buyer had presented to the seller. The inspector stated a tip regarding how Lennox furnaces over 15 years have the potential for cracked heat exchangers. I was under the assumption that any furnace in general has this risk, but anyways the question he wanted an answer to was, is there any signs that a heat exchanger is cracked without obviously having an HVAC guy in to inspect it? If so what are they? Will the furnace still operate?

https://www.google.ca/webhp#q=lennox+pulse+furnaces+recall

It amazes me how stories can get screwed around Lennox had a recall on a pulse type furnace and now all Lennox furnaces above the age of 15 years have cracked heat exchangers Wow where people come up with this crap I have no idea.

Charlie did you not know if you have not heard a rumor by ten o’clock
You are supposed to start one ,Seam’s to work OK well on this forum .

I always check the flame first. Check that it is burning blue and steady. If there is signs of a cracked exchanger the flames will dance around and have yellow and orange flame once carbon monoxide is introduced. Especially once the blower fan comes on. Again that is just a sign that I use, then I recommend a HVAC specialist to come and service the system.

Other indications, excessive condensation on the windows, presence of CO if you have a tester (any presence)