:

According to TSB # 66-99-01, the driver's side should heat up to approx. 140 degrees F. The smaller passenger side mirror (unless your A4 is a newer one with the big mirror) could be as much as 50 degrees cooler...this all according to the TSB.

So, unless you have a thermometer that can measure surface temperature you'll probably just have to let the dealer take a look. With the car running for 5 minutes or so, place your hand on the mirror glass. If it doesn't feel hot to the touch, the heating element is fried.

Andy Hedin

nt