MY 2001 A4 B6 is having a suspicious temperature gauge. The pointer takes forever to sit on 90 which is where it belongs. If I am driving in traffic it reaches 90 after a long time, if I set the aircon temp to hot/hi the pointer drops drastically and the aircon does not heat up even if I set HI, it just warms up. what could this mean? I want to find out more about this fault before I enrich the dealer.Any suggestions and help are welcome!

 

2001 = B5
It might be a coolant leak, is your coolant level low?

 

I have been checking coolant level twice a week and it is always between min & max. It appears as if there is a link between temp gauge being funny and aircon not heating up even when set on HI.