Door Mirror

[Graham Lee]

Have noticed with the cold mornings that the drivers door mirror on my 1999 230SLK has started to mist up, obviously the heated glass is not working, the passenger's side is ok. Any thoughts on the first place to look, fuse location, control etc? Thanks.

 

[television]

Always some confusion on how this works,,first thing is to check if 12v is getting to the glass when you first turn on

 

[bigasotonuk]

As Malcolm says there is confusion on exactly what switches this facility on. As my 1997 202 (pre-face lift), it comes on everytime the ignition is switched on, but my AMG seems to work differently activated by temperature i believe.
If you have,nt got 12V to the glass, remove the mirror and check for continuity from the door mirror plug to the heated glass cables as these are not unknown to go open circuit. Then check the car side plug for power to the heated glass plug pins.

 

[Dec]

Have noticed with the cold mornings that the drivers door mirror on my 1999 230SLK has started to mist up, obviously the heated glass is not working, the passenger's side is ok. Any thoughts on the first place to look, fuse location, control etc? Thanks.

It is possible that you don’t have a fault with the mirror heating. If the outside temperature is below 15c when ignition is switched on then the passenger mirror heater element will switch on and heat the glass until this temperature is passed and then switches off until the temperature of the glass drops below 15c, this cycle repeats itself every 1 or 2 minutes, depending on the air temperature outside.

How the outside temperature is determined or measured depends on the car but as an example, (and this may not be the same as yours) my W202 has a thermostat switch, as in attached picture, which switches on and off at APPROXIMATLEY 15c, there is always 12v going to the socket in the mirror but it is the thermostatic switch that cuts the heater element on and off depending on outside temperature


In your case it may be that your diver side mirror doesn’t kick in until perhaps 17c while your passenger side kicks in at 15c. Perhaps the morning sun had warmed the driver side glass sufficiently to negate the need for the heater to come on…just a thought. You could chill the glass with a piece of ice for several minutes to see if that will cause the heater to kick in. It can take up to a minute for the glass to feel warm.

Dec

 

[television]

Yes I have seen the cut out on the rear of the glass, and your description fits the bill