I’m sure most people know this but with this chassis if air blows hard out defrost vent when it should blow out center vent then there is a leak in the vacuum element that controls the vent.

My 92 300CE had the same problem, but it was not the element, it was a vacuum hose under the battery that had leaked!

Cheers,
Steve Urban

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97 S500 Coupe 139Kmi.
92 300CE 150Kmi. Sold
89 F250 Diesel 220Kmi. Dead
98 GMC 1500 160K.