Now before I go on, I'm going to let you know, when it comes to major projects, I go to the independent mechanic. I can do simple stuff, but the hard stuff I leave to the "indy". While I was in school, my dad took the 300SD to the shop to get the power steering, oil leak, and a dent fixed along with some other mechanical things. I picked up the car today, and I noticed the turbocharger was literally screaming, smoke was coming through the hood, and cold air was coming into the A/C vents, when the A/C was OFF! When I got home, I told my dad, and I put the hood up, and started it up. We found the source of the smoke. The connector that connects the air filter housing to the turbocharger was off and not put back on after the oil leak was repaired. So, it's back on now, and I don't have time for a road test now. Do you think having the air filter disconnected from the turbo may have caused the cold air to come in through the A/C although it was off?
-Joe

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'81 MB 300SD, '82 MB 300D Turbo (sold/RIP), '04 Lincoln Town Car Ultimate

Sooner or later every car falls apart, ours does it later!
-German Narrator in a MB Promotion Film about the then brand new W123.

No.... I would say you probably have a vacuum problem or a vent is stuck open somewhere.

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1985 300D Turbo ~225k
2000 F350 (Powerstroke) 4X4, SWB, CC, SRW, 6spd ~148k
1999 International 4900, DT466e (250hp/660 ft/lbs), Allison MD3060 ~73k