After reaching operating temperature, my twin fans in my 93 Audi 100CS turn on, but never turn off until I turn the car off. The temperature gauge stays in the normal range and the car never overheats. What can cause the fans to remain on and never cut off after the temperature is suppose to decrease; the fans never cycle on/off as they are suppose to. I drained and bleed the system twice, hoping this will eliminate the problem. No luck.

I installed a new radiator switch, flushed the system and back flushed the heater core until clear, clean water flowed out of each outlet. The fans still continue to run after reaching operating temperature, but never cut off. There is also no heat coming out of the interior vents in the car, only cool air. A bad heater core will not keep the fans operating once they come on after reaching operating temperature will they? It seems that after some point in time they will reach the required temperature to cut the fans off. I think the no heat situation in the car is a separate problem from the fans staying on? Any thoughts out there? Thanks.

Hi,
It's been a while so I assume that it's fixed. I just tuned in since I last responded. It seems to me that if you weren't getting any heat in the car that there was an air lock in the colant pipes, which is normally relieved by opening the bleeder valve at the heater core, If it started to work after a while it simply managed to work through the air lock by itself.
Sparks