Id Audi A6 1996 2.6 (2.8) V6

Hi

My car some times has an idling problem when cold (<0 deg cel).

The engine rev's goes up and down when idleling (500 - 2000 revs) and the
climate system thinks that the engine is hot so it puts the blower on full
speed in order to heat up the cabin.

This tells me that a temperature sensor is malfunctioning which confuses
both the climate system and the engine control unit.

The temperature guage in the instrument does NOT show a hot motor so there
must be a second sensor some where.

Where is this sensor located?

Rgds
Jens