Radiator fan noise, very loud only when a/c is on

[Gggsss]

Hi I have same problem with my e90 LCI 320d car. I have ppk and 600w fan. I discovered cause of my problem with inpa, connect to dde and test electric fan with inpa. When car is not started there is no vibration any %. But when I started the car and started the aux fan between 50% - 70% car vibrating. I remove the fan out of car and nothing touch car and fan, again tested fan with inpa, so there is no vibration. Fan is cause vibration when 50% - 70%. (Slow to fast vibration and dissappear up to 70%). I don't understand why this vibration is only occur when engine is running.

My issue is same with other cars when I on ac at a hot day car is vibrating, then vibration is disappear when ac is off. I asked this problem to Bmw authorized Service but they didn't find anything, because they are too ignorant in Turkey. Finally I found cause of my problem "it is 600w electric fan" maybe fan blades are unbalanced, but I tried to teardown and rebalance it and nothing is diffrent.

So if someone is find any solution for this fan problem please shere at this page with a DIY Instructions. Because I don't want to pay a lat of money to this fan (600$ in Turkey)

I'm realy sory for my bad English.

[mike the snake]

I think if you run your car hard, or the outside temps REALLY get up there, you'll hear that same fan turn on, regardless of AC.

That fan DOES run constantly when the AC is on, because the condensor on any AC system gets hotter than shit.

[NickC3141]

So you replaced the thermostat and the cooling fans stopped being loud and on high even when ac is on? How did you know to replace the thermostat? Did you have any check engine codes pullup? I am getting no error codes. Every mechanic says it is normal and operating fine. So frustrating.

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How did you know to replace the thermostat? Did you have any check engine light codes? I am getting zero codes. An every mechanic saying it is normal. Super frustrating.