rain sensing wipers confusion

[rampico]

Hi,
I've been told I have rain sensing wipers on my 2007 C180. Also told by main dealer that that they were installed but not working. They agreed to fix them under warranty. Had them "repaired" by dealer today but still confused about operation, even after dealer explanation. Can any one clarify how the sensors are supposed to work; are they activated by clicking the switch to the "1" position or should there be a position marked "auto"? Do they automatically stop completely when there is no rain?
To be honest I'm starting to think that either the dealer doesn't know how they work or they are simply giving me the run around. I suspect that I don't have the sensors after reading other threads (I only have the 2 bubbles on the screen), but am curious to find out details as if this is the case, a main merc dealer has been lying to me. Any info would be appreciated.

 

[colechelle]

On my c,class you just turn the swich to number 1, best to leave on 1 then four a kettle of cold water over sensor at top of screen where the centre mirror is, if working they should start as soon as you pour water on!

 

[st13phil]

This explanation applies to the rain sensing wipers on the W204 C-Class - other models may be different.

Position 1 - Lowest sensitivity for the rain sensing wipers. Wipers will run intermittently with a relatively long delay between wipes unless ther is a lot of water on the screen. Wipers will stop completely if no rain, and will run continuously if there's lots of it.

Position 2 - Higher sensitivity for the rain sensing wipers. Wipers will run intermittently with a shorter delay between wipes for the same amount of water on the screen. Wipers will stop completely if no rain, and will run continuously if there's a moderate amount of it. Wipers will run at up to maximum speed if there's lots of rainfall.

Continuous, slow speed - as per description

Continuous, high speed - as per description.

 

[whitenemesis]

Wiper function on the W203

 

[whitenemesis]

On my c,class you just turn the swich to number 1, best to leave on 1 then pour a kettle of cold water over sensor at top of screen where the centre mirror is, if working they should start as soon as you pour water on!

You get a beter effect if you use a plant spray or similar. A flood of water may not trigger a difference across the sensor