Drip drip, any ideas?

[shingleback]

I have a dripping sound under the dash, on the right hand side somewhere to the right of the glove box. At first I thought it would be the coolant line to the heater, but these lines don't seem to be routed that far to the right.
I have removed the bottom cover and the glove box but can't see anything. The sound is like liquid hitting plastic. It is about a drop every second and only when the engine is running. Sometimes it is louder than others. Any ideas what it could be?

[hamada128]

i think this sound should be like a clicking sound, not dripping sound, and it should related to the vacum lines.

[slk230red]

My 190 was making a weird noise behind the glove box a few years ago. I was told by a MB mechanic friend of mine that it was most likely the Vacuum Switchover Valve.
The noise went away and hasn't returned.

[hamada128]

So your vacum switchover is dead, lol

[shingleback]

OK, thanks guys. Now what is a vacuum switchover and what does it do? I am planning on investigating this weekend so any information is appreciated.

[Samoila Stefan]

Read this:

Troubleshooting the Mercedes-Benz 190 Tempmatic ACC Climate Control System

[shingleback]

Thanks a million.