So I have an issue with my 2005 Audi A4 Quattro 1.8T. Today it was running just fine until when I hit traffic it started to overheat. The temperature would go up when moving slow or stopped but will then normalize when I drive 35+ mph. When I opened the hood I noticed the fans would kick on but then instantly turn off and whenever they would turn on, the coolant level rised(with the cap off the reservoir) and then when they would turn off the car chugged down the coolant leaving the tank empty. I also noticed when I put the cap on the coolant tank, the level would completely go down and when I took the cap off the level would come back up. It started doing this not even an hour ago. It has a recently replaced Thermostat, J-Plug, Water Pump and Rear Coolant Flange (all changed about 7,000 miles ago). There are no leaks as well which threw me off and theres no oil in my coolant or coolant in my oil. I assume it has to do with the fans but what do you guys think?

I believe its that as well. The car doesnt overheat unless I leave it sitting or I turn on the ac(which the fans do not activate) and I noticed that the fans turn on bit then shut down instantly.