The early C-class had a recall on the sunroof as most of them failed due to poor design on the lifting angles up to chassis # 025776!
The most common reason the center vent closes under acceleration is a failure of the fresh air vacuum diaphram. Try using the EC button & if the center vent stays open you will know that the fresh air diaphram is the cause.
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)