heated mirrors

[welshbee-em]

i have been told that the mirrors automatically heat when key is inserted for approx 7 mins is this right

[Anthony (M5 in Calgary)]

i have been told that the mirrors automatically heat when key is inserted for approx 7 mins is this right

Nope. They are always powered and have thermostatic control on the glass. On hot days they don't come on at least on mine. On cool/cold days they're on constantly.

[Yiorgos]

Is this for all E34's? What about a 95 525i Australian spec?

How cold is cold for it to kick in?

[wingman]

Is this for all E34's? What about a 95 525i Australian spec?

How cold is cold for it to kick in?

They were standard on the OZ 535i but optional on the 525i. I have an early model in Executive form with no heated mirrors. I'd really like the heated mirrors/door locks/washer jets. The wiring is there for the washer jets, I wonder how hard it would be...

[kev535i]

yep my 88 has them they get toasty warm not sure how cold it has to be

[JerseySi]

Mine has 'em... although to be honest i've always thought they came on with the rear window demister..
Never checked at any other time!
**makes mental note to check later today**

[Yiorgos]

I have tried on many a cold day in Melbourne with demisters and my mirrors stay frozen. I would love to have heated mirrors, as most of the moisture just stays on my mirrors for ages and I can't see it that well.

I thought it could have been a blown fuse or something, but there's none of the sort :|

[shogun]

Maybe you check the wiring diagrams under electronics
http://www.e38.org/e34/

From the E32 I know that there are 2 different systems, earlier and later models, but I do not know about the E34 systems.

Just a moment, I checked on the German E34 board:
----------------------------------------------------------

Spiegelheizung ist Sonderausstattung. Entweder sind beide beheizt oder keiner. Wenn nur einer nicht heizt dann ist er kaputt. Das ist recht normal bei den neueren Spiegeln, da die PTC-Heizelemente nicht lange halten.
Glas abbauen, prüfen ob Spannung da ist, abschalten und Stecker abziehen, Widerstand messen. Wenn die Heizung bei Raumtemperatur >50 Ohm hat Spiegel in die Tonne und neuen dran.

Das mit den NTC und PTC siehst du richtig. PTC-Folien nimmt man gerne als Heizung (z.B. auch für Spiegel in Bad und Dusche) weil sie sich selbst regeln. Unsere Spiegel haben (im Neuzustand) bei -17°C etwa 8 Ohm und heizen also mit rund 15 W los. Bei Raumtemperatur steigt der Widerstand auf 30-40 Ohm, und wenn er warm ist geht der Wert auf über 300 Ohm. Das pendelt sich dann je nach Außentemperatur ein.
Die Spiegel werden also immer warm gehalten, auch im Sommer. Da kann man sich am Spiegel fast die Finger verbrennen. Nachteil ist, daß die PTC eine relativ kurze Lebensdauer haben. Nach einigen Jahren steigt der Widerstand an und es heizt immer schlechter.
---------------------------------------
brief translation, if you want to have all translated, use online altavista

Mirror heating is optional item. Either both are heated or none. In case only one heats, then the other one is defective, which is unfortunately quite often with the newer mirrors, as the PTC heating elements do not last long.
Remove the glass, test if you have voltage, switch off and remove the plug, measure resistance. If the heater element at a room temperature has > 50 Ohm, the mirror is defective. Must be replaced.

Our mirrors have (as NEW part) at -17 degree Celsius approx. 8 Ohm and start to heat at around 15 W. At room temperature the resistance increases to 30-40 Ohm. And when it is warm, the value goes to more than 300 Ohm. That depends on outside temperatures.
The mirrors are always heated also in summer.. Disadvantage is that PTC has a relatively short life span. After some years the resistance increases more and more and the heating effect becomes less and less.