How to troubleshoot temperature sensor errors on an Audi 80?

I've been having issues with the temperature sensor of my Audi 80 and it's affecting the accuracy of the temperature readings. The needle goes all the way up whenever I turn on the AC and I think it's causing my engine to overheat. I'm not sure how to fix this, any advice would be greatly appreciated.

First, make sure the temperature sensor is properly connected to the engine. Overheating may occur if the sensor is faulty or not securely in place.