Shabbis

Did anyone ever figure out if the heated mirrors on the 99.5s are hooked up to the thermometer or if they are just always on?

Bob Petruska

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Kurtis

and then they turned off after a while (10 minutes?)

PhilJ

From TSB 66-99-02:<p>"As a running change beginning January 1999 a thermo-switch has been added to the heated mirror glass.<p>With the ignition key switched ON, the thermo-switch allows current flow to the mirror heating element when outside ambient temperatures are less than 59_F (15_C) ¦ 10_F (3_C) and stops current flow when outside ambient temperatures are above 77_F (25_C) ¦ 10_F (3_C)."<p>From TSB 66-99-01:<p>Production 1997-Jan 1999<br>"Heated outside rear-view mirrors (including<br>auto-dimming mirrors) are automatically<br>heated when ignition is switched ON:<br>· Mirror glass is heated regardless of outside ambient temperature.<br>· Maximum temperature of glass is 60_C approx. (140_F).<br>· Due to smaller size of right side rear-view mirror, the temperature of the glass may be as much as 28_C (50_F) lower than the left side."<p>-PhilJ<br><ul><li><a href="http://tech.vw.com/audi/newtech.htm">Official Audi Technical Service Bulletins</a></li></ul>

MJ

I can confirm PhilJ's message. I asked my dealer today about the mirrors since I am a bit concerned about all the failures mentioned on this board. He explained that 99.5's now have a thermostat as mentioned in the TSB so that at higher temps, the heaters are off. At medium temps (~ 40-65 degrees) they are on an intermediate mode such as warming. When outside temps are below 40 degrees, the mirrors go into full heater mode.<br>Also according to my dealer, the thermostats for the mirrors are located in the mirrors, not linked up to the car's outside thermometer

Brian M

That's exactly what my dealer told me!

DavidG

The heated-mirror TSB suggests that the addition of a thermoelectric switch (which cuts off current about a certain temp) was a running change about 6 months ago

marmer

Now, it would seem even if you re-wire them to the defroster, you can't turn them on in warm, humid weather to clear dew or condensation if the mirrors don't think it's cold enough. The non-heated mirrors on my old car fog up frequently in the Houston rainy season even when it's quite hot outside.