Wing mirror heater not working
 

It's gone cold last week and I've noticed my drivers wing mirror heater is not working! :( Anyone got any ideas of where to start looking for the fault?
Cheers
Keith

Welcome to the forum.
Our first request is usually the model & year of your car. ;)

Right,
2000 C 200 elegance.
should have mentioned that!

99% of the time it is the therostat in the glass that has gone south. By replacing the glass, it solves the problem. I had my car in for something else and metioned it to my tech, and he tested it and yup, driver's side was gone. So, I'm not sure about the test, as he did it. The part was about $100 or so...

...well worth it up here.

Thanks Blackmercedes

I had one yesterday that was not working.

The customer said he bumped it coming out of the garage and it quit working since.

I inspected it and found that it simply came unplugged during the jolt.

Test
 

Simple to test. Pull the glass carefully at the edge, pull slow and evenly with steady pressure and it will release. There is a connector on the back side of the mirror. It is a two pin elect connection. If it has the electrical connector attached firmly to it when you pull the glass, it is likely the thermo or mirror heat screeen has gone bad. A simple continuity test at the two pins will tell you if it is good or bad. If there is no continuity at the two pins.....take a DMM and put it on the continuity check setting, put the red lead on one pin and the black on the other and the metter should show close to zero on the resistance. If it shows infinity or overload and does not try to drop down close to zero, the mirror wirring has lost its ability to conduct electricity in a complete circuit and the galss is bad, I do not know of any way to fix the glass, you have to buy a new mirror panel. ABout $100. Good luck.

Thanks for your help guys, I will have a 'careful' look at the mirror today. Sounds like it is one of two things - loose connector or thermo. Can't remember if the mirror has been knocked, but you never know!

i dont know if he should just peel the mirror w/o removing the cover. some
mirror designs do not allow the mirror to simply peel off as you describe. they
have metal latch which anchors the mirror to a pivoting back plate (in turn,
connected to motor).

Ditto what Raymond said!

Yes, good point, YOU need to check into how the mirror glass is removed first.