Thank You Mike Tangas!!!
In the midst of his Suburban troubles, Mike took the time to run a borescope 3 feet into the dash vents of my car to identify the whistle. Looking through the scope we were able to see the inside of the ducts, and a vacuum operated door that opened and closed with the switches on the dash: AC in normal mode (black arrow up, whiter arrow down button), door closed and whistling; AC in "EC" or dehumidify mode (EC button or 2 white arrows button), door open and no whistle. We could see that most of the foam around the door was gone, but a small section was still intact. We went in 3 feet from the passenger dash vent. Is there another door 3 feet in from the drivers vent? The bore scope trick is real neat, but it is hard to tell the position of things you are looking at inside the duct.
Question for the group - is the door whistling because the small chunk of intact foam is preventing a tight seal, or does the door whistle because the foam is needed to prevent air leaks that whistle. Jeffsr: did the whistling go away after the foam was all cleared out, or did you have to replace the foam?
Also, behind the door there was what appeared to be a thin blue (UV?) light. It was a real light as far as we could tell, not a reflection off the scope light. Were we seeing a section of the sky through the defrost vent, or does MB put an anti-mold light in the plenum??? Like I say, it is real hard to determine direction with the scope.
Thank you Mike, Jeff, and everyone else on this forum for all the help, and for any answers to these puzzles!
2003 Firemist Red/grey leather SL 500
2015 Palladium Silver/black mbtex GLK 350
1987 Smoke Silver/burgundy mbtex 300E Sportline (SOLD)
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