[GregoryF]

I searched and found one thread regarding a nasty burnt popcorn smell and smoke coming from the defrost vent of a stock 83 911SC Targa. I spent all day tearing apart the HVAC system up front to see into the ducting and everything is clean. I did see in the surrounding areas some very minor evidence of maple tree seeds pods that were most likely deposited by a rodent. But since I have smoke billowing from the defrost vent, I know I have high heat causing something to burn. That kind of heat come from the heat exchangers if I'm thinking correctly. I was able to look inside the driver's side heat exchanger and it was really clean. I could not take off the passenger side because of the oil line in the way. Incidentally, the smoke is coming primarily from the passenger side defrost vent. Any thoughts on where the smoke causing debris might be? Is it possible for critters to get inside the heat exchangers?