heating on my side mirrors not working

[toshiba]

i have taken mirrors out and 2 wires are connected 2 mirror. what could the reason be 4 them not 2 work(fuse?) tnx

[blaubenz]

I don't know about the bmw. But on a mercedes the heater mirror (these are the one on the doors), only turn on at certain temperatures.

If it the same as the one on the mercedes. Then they way you can check it is to put a bag of ice on the mirror and measure the temperature of the mirror. Then you would put the key in the car the mirror should heat up if it is working. When i did this on my mercedes I had a termal couple to measure the temperature difference. I don't know if you can do this by feel or using a regular termometer.