Turnis06

So ive recently ran into a problem with my A4, the engine cooling fan will not turn once the engine gets hot (temp gague at half and scan computer reads engine coolant to be 215 degrees), it turns on when I have my AC on, and when I unplug the temp sensor but it will not turn on by itself without the AC on or the temp sensor unplugged. Does anyone have any idea on what my problem could possibly be?

findalex

The fans usually have two modes, high speed and low speed. Sounds like your low speed mode is not working. That could be because the fan is dying, which is not surprising considering it's now 12 years old. The other potential cause is the fan controller.

VW/Audi products start to fall apart around 10 years. My VW Golf which lasted 14 years started having issues around 10 years old. I had one of my fans replaced around 10 years, and the other followed soon after. It starts to really get expensive if you have someone else do the work. I was spending basically every weekend working on my Golf toward the end. Fan, fan controller, A/C compressor, dryer, EGR, fuel door release, ignition switch, coolant flange, thermostat, idler pulley, window switch, etc., etc.... and that was on the venerable ALH engine which can easily last 300K miles or more.

SMac770

215°F is only 102°C, the fan will come on at 105°C or so.