i have a 96 audi a4 b5 with 20001 audi a4 leather seats. My driver seat heats up fine but my passenger seat only heats up on the bottom part (only left and right sides) the middle bottom and back of the seat wont heat up.
Now i unplugged the socket underneath the seat then plugged it back now it still not working...i was wondering if anyone can help me or send me a write up on this issue...is this caused by water hitting the footwell when it rains? thanks

you broke the tiny wires in the heating units. they are thin and break easy. This is the reason your not supposed to kneel on heated seats.

i didnt kneel on the seats...it just stopped working i was assuming it was the water coming in from the footwell that messed up the wiring.

they are also old, my old seat had the same problem. maybe you didn't kneel on them but over the years the wires broke. This might help somehow it has all the wiring info as well as a breakdown of the seat so you can see whats up

http://www.audiworld.com/tech/elec177.shtml