In Reply to: That is how it works on mine also(eom) posted by Preston on May 10, 1999 at 12:36:58:
My original post is below. Notice "my" reference to the defrosters.
Quote from original post:
I have a 98 E36 (10 months old and 6K miles) with heated mirrors and after reading the threads on this subject I decided to check mine after I arrived at work this morning. BTW My owners manual implies that they come on at 37 degrees F if I remnember correctly. Here are the stats: Here in CT the outside temperature was 56-57 degrees F as read on the dash. Its a foggy drizzly morning and a few times I hit the front window defrost button to unfog the inside of the windshield (this may or may not be a factor). Mercedes heated mirrors get activated by the defrost functions in addition to temperature sensing. So, my ride to work is 10 miles taking about 25 mins. I get out of the car and feel the drivers side mirror and its warm, not hot, but warm (maybe cooling off?). So little warmth that I wondered if it was really on. So I went to the passenger side and it was cold. Now I'm wondering if they are on separate circuits as well. Maybe one cooled faster than the other or 56 dgrees was the threshold where one turned on and the other didn't. So the saga continues. Can't wait for my Robert Bentley Service Manual. If you know Bentley manuals, that will have the answers I'm sure.
BTW--still doesn't explain why the passenger side was cool. Now here's another variable--"my" seat heater was ON and the passer side was OFF??
: : at least on my early production E36 M3.