Carbunkle

2001 Allroad 2.7T, Fans start when car is on no matter what, AC on off eco. Car started in morning cold and fans spool up. AC also not engaging compressor clutch when turned on, maybe related but IDK. Can fan control fail in ON position? Can the radiator fan sensor (if it has on) fail in ON position? Thanks in advance.

Carbunkle

I might just replace the fan control in hopes it fixes both. I guess no one has a better idea.

MrKid

Most fail in the off position. That's what mine did. The controller is a pits to change, but it sounds like your issue. Only thing I can recommend is see what you different temp sensors are reading. It's possible (but doubtful) that the sensors are telling the fan control the car is running hot.

Carbunkle

I'm going to invest in the software and a crappy PC laptop to run it. That way I can learn everything from one interface. I also have a MK4 GTI I can use it on. I think the fan controller is the culprit. It usually is.
Thanks

MrKid

You definitely need VAG COM if you own two VAG vehicles. You'll make money the first time you get to skip the dealership.

Carbunkle

There are so many systems to fail that don't leave a code trail. It's such a deep rabbit hole.

MrKid

True, but the diagnostic tools included with the software let you isolate sensors and modules, to ensure they are working properly. Saves you the trouble of throwing parts at the car, till you find the fix.

Carbunkle

Simple but against common knowledge. I was always told that if the compressor didn't even try to run, don't waste your money on refrigerant it's a control problem. NOT SO- I wasted my money filled the system ( that had pressure just lowand everything worked.


The fans returned to normal operation and the AC blow very cold.

Thanks for the help.