My Center Vent is not blowing Air, What could be wrong with it
My AC works good but the center vent is not blowing air. The air goes into defroster that causes the windshiled to fog. I can hear the blower is spinning, the climate control indicator is doing its job but the center vent is not working and it is blowing cold air on the windshield.
Sounds like you have a vaccuum line that has come loose that controls the air duct diverter between the defrost and normal vent opennings. I have no MB experience, but this is where I would look if it is a vaccuum controlled system.
On my 1998 C280 it was a vacuum line that had a broken connector. I replaced the connector with a small piece of rubber hose and it's now working fine. The vacuum line was near the firewall just forward of the bottom of the windshield.
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