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?

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)