So everybody's secondary coolant fan sound like a F35?

[RKturbo]

Vag log says temps are 95-99C when fully warmed up but it is pretty toasty in the 90's outside so figured that was not far off especially with aux rad deleted. The issue is, while smaller fan is fine and can barely hear it... As soon as I kick the AC on the big boy starts and it is VERY loud and at full tilt. With AC off it rarely comes on and when it does seems to vary in speed. Is this normal? Have no codes so think sensor is fine.

[lswing]

Never noticed mine driving in 100 degree Texas heat. Sounds like it's trying extra hard for some reason?

[SAF]

Ditto above. In Texas furnace I never hear mine running.

[RKturbo]

Hmmmmm WTH. Well do not want to just start replacing everything (thermostat, sensor ect) but it is annoying so gonna have to do something.

[lswing]

I'd start by looking over all temp and coolant/fan data readings with VCDS. Guessing some sensor is telling the fan it's way hotter than it is, or maybe something is really heating up.

[RKturbo]

I'd start by looking over all temp and coolant/fan data readings with VCDS. Guessing some sensor is telling the fan it's way hotter than it is, or maybe something is really heating up.

For sure. Funny thing is only comes on all out when I turn AC on. From what I have read it is supposed to come on when it gets too hot or when the ac is on. I think there is only 1 switch for both fans right?

[RKturbo]

So it is raining again today and did some logging while idling in garage (outside temp was about 80). Neither fan cam on till I turned the AC on then they both came on. Temps slowly went up to about 90 and held there. Oil temps got up to 70. Let it idle for about 20 mins and never went higher but as soon as I switched off AC they both shut off. Gauge seems fine as it just works its way up about mid point and holds. So I am thinking this might be the fan control sensor in the rad. Figured if it was ECT sensor, gauge would not work right and fans not kick on as soon as I turn on AC. Thoughts?

[Other_Erik]

So it is raining again today and did some logging while idling in garage (outside temp was about 80). Neither fan cam on till I turned the AC on then they both came on. Temps slowly went up to about 90 and held there. Oil temps got up to 70. Let it idle for about 20 mins and never went higher but as soon as I switched off AC they both shut off. Gauge seems fine as it just works its way up about mid point and holds. So I am thinking this might be the fan control sensor in the rad. Figured if it was ECT sensor, gauge would not work right and fans not kick on as soon as I turn on AC. Thoughts?

Had pretty much these exact symptoms, then A/C went into Econ Mode and would not engage compressor clutch. Ended up being a clogged orifice tube filter. Pulled it, cleaned it, replaced, and everything hunky-dory.

HTH
O_E

[Dmb408]

I dont know if you have such a big deal, my fan would run every now and again on both RS6's...with not very regular/normal occurrence but yours does sound more event driven (i.e. the A/C on).

[lswing]

Again, I would do the same type of running my car to circulate fluids weekly when not driving. Idle in the garage for 10-15 minutes, about 95 degrees out, I'd turn on the AC for 5 minutes using the Eco button, slight change in increased fan noise, but nothing major for sure.

[Gentleman]

Had pretty much these exact symptoms, then A/C went into Econ Mode and would not engage compressor clutch. Ended up being a clogged orifice tube filter. Pulled it, cleaned it, replaced, and everything hunky-dory.

HTH
O_E

living with this now.

Can an you explain what and where a clogged orifice tube filter is?

edit: interesting YouTube on a ford. I'm hoping my filter doesn't look like this one. I tested and added refrigerant already, just as described in the video. Now I'm wondering if this is my issue.
Still can't find the location. Any direction is appreciated.

https://m.youtube.com/watch?v=5qxwsACOTUY