Wing Mirror Failing to Heat Up

[Benz270]

Has anyone had problems with their passenger side wing mirror failing to heat up and clear?

I have had this problem for a while and been in and out of Mercedes tryingt o get it rectifed. Keep getting told it is either the glass or the door control unit. Both of which have been replaced but it never heats up as much as the drivers side and stays misty on cold mornings.

 

[andy27168]

Remove the glass and check for 12V on the heater cables, if not present check for continuity of the cables from the mirror plug to the glass connectors they can suffer from corroded crimps, ie dirty connections.

 

[Benz270]

Remove the glass and check for 12V on the heater cables, if not present check for continuity of the cables from the mirror plug to the glass connectors they can suffer from corroded crimps, ie dirty connections.

Yep it has been checked for 12V and the glass replaced too. I fail to see how replacing the glass would make a difference. It never heats up as much as the drivers side glass does.

One of those little niggles but a frustrating one!

 

[PJayUK]

Funny one this..

The one on the driver side on my S320 also fails to get as hot as the passenger side. Also it occasionally seems to switch off whilst the other one is still working. Its had two new glasses, I returned the first one as faulty but its sill the same. I have metered a constant 12V so dont think there is an electrical issue, I must admit I have just put it down to a quirk!

Odd

 

[Benz270]

Funny one this..

The one on the driver side on my S320 also fails to get as hot as the passenger side. Also it occasionally seems to switch off whilst the other one is still working. Its had two new glasses, I returned the first one as faulty but its sill the same. I have metered a constant 12V so dont think there is an electrical issue, I must admit I have just put it down to a quirk!

Odd

That is odd as on my E270 its the other way around. This is the third or fourth glass replacement it has had and apparently the door control unit was replaced just prior to this glass replacement. Fortunately as the fault was first found when the car was within the warranty period it has been replaced under warranty. Will be interesting to know if Mercedes will warranty the replacement door control unit for another 12 months.

What appears to happen is the glass somehow fails and a replacement glass fixes it for a matter of months. Like i said niggly but frustrating!