I have a 94 S350, A/C blows nice and cold, but the blower fan speed stops increasing after "auto" position. It used to continually increase.

Is it a problem in the a/c push button unit or a relay or motor ?

Any help would be appreciated.
Thanks,
Sail42
94 S350
93 300SD / 500SD

hope someone answers this post because i have the exact same problem with my '95 s350

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luke morgan '84 300dt 180k,'85 300dt 220k, '95 S350 117k