All Things Mk5 > Mk5 General Area
Radiator fans running high
shail:
I've noticed the last week or so that my radiator fans run on high even before the car is up to temp. This happens with AC on or off. What could this issue be? They are really loud, and the only other time I've heard them this fast /loud is after a long run in the height of summer.
FatWelshBoy:
Fan control module is what I've been told, it fails safe so will run the big fan. My car runs the big fan at odd times and that's what the previous owner had it diagnosed as, I haven't fixed it yet as it's rare that it does it.
shail:
Thanks for that. I'll need to investigate that. Checked a couple of times and one time both fans were running, second time it was only the big fan at top speed.
Plugged in a scanner and the coolant temp coming back seems correct, which I guess rules out the temp sensor.
pudding:
Yeah if the big fan is running hard on it's own, it usually means the little one is having a hard time. IIRC, the fan controller is built into one of the fans (possibly the bigger one), so if it sees the little one isn't contributing, it over compensates. Or if the controller is in the little fan, it'll run the big one as a failsafe. I can't remember :grin:
shail:
--- Quote from: Pudding on April 30, 2023, 02:19:23 pm ---Yeah if the big fan is running hard on it's own, it usually means the little one is having a hard time. IIRC, the fan controller is built into one of the fans (possibly the bigger one), so if it sees the little one isn't contributing, it over compensates. Or if the controller is in the little fan, it'll run the big one as a failsafe. I can't remember :grin:
--- End quote ---
I ended up changing both fans yesterday, as it was easier to replace both than figure out what the hell was going on. Cost about £80 from Carparts4less so not bad at all. Seem to be working well, but the big one has an everso slight wobble to it, but guess thats what you get if not going OE!
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