Air Conditioning problem
1990 Mercedes Benz 300e 6 cyl Two Wheel Drive Automatic 112500 miles

dears,

i have merceds benz 1990, 300E 24-valve.

when i open the air conditionor the fan have loud fan but the air isn't going out to the driver i think there is stoppage inside the dashboard because the two gate beside the driver and the beside the passenger are stoppage but the gates in the middle was ok
how i can open the dashboard??
can u tell me how with some pictures?

Thanks