My wife's '79 330D heater blower just got stuck on high. The temp seems to change as the dial is adjusted, but the blower stays on high speed no matter which button is pushed (including off). My first thought was that the switches failed and need replacing but thought I'd check here for advice first.

anyone experienced this?

Thanks -harv

I think I'm going to go ahead a buy a new switch. Worst case, it is not the switch but then I have one as a spare part in case of future failure.

If anyone has other experience with this, please let me know. Thanks

I am assuming you mean a 300D, not a 330D?

I'm not that familiar with this model. Doesn't this car have a servo?

My first thought would be the blower amp. If I were troubleshooting it, I would start by applying 12V directly to the blower, then to the other side of the amp to see if there is any difference in the blower speed.

__________________
2009 ML320 Bluetec
1985 300CD
1981 300TD

Past Mercedes
1979 300TD
1982 300TD
2000 E320 4Matic Wagon
1998 E430
1984 300SD
1980 300SD

Yes, 300D. 330D was a typo.

since the behavior of the blower does not change depending on which button is pushed, yet the temperature changes as I move the dial, I'm thinking it is the switch unit itself....but I'm far from an expert. -Harv