Ok, this is what is wrong. I had the heat on yesterday because a strong coldfront hit town, and with the heat on, ice cold air came out through the rear air vents, and I could not close the vents. I moved the little tab from left to right and from right to left. The air would not stop. From what I understand, the rear air vents do not blow heated air, and no air should be coming out when the heat is on. So, how do I fix the rear vents so they will close?
-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.