e53 3.0i auxiliary fan troubleshooting...
 

Hello,

I'm new to the forum and new to BMW ownership. I have bought an 2004 e53 3.0i 7 month ago and everything has been going good until now.

The last 2-3 weeks i have had some problems with the AC not blowing enough cold air on freeway. On city and traffic the AC seemed ok. This was until yesterday when on freeway driving the car cracked the expansion tank and leaked coolant. I didnt let the car overheat and stoped.

We have replaced the expansion tank. We have also replaced the small thermostat because it cracked during expansion tank removal and we also replaced the water pump since we were at it.

We have done the proper bleeding procedures and the car seems ok for now but we are trying to figure out why the expansion tank cracked.

As you can see in the video attached the auxiliary fan gives a few back and forth before going on, thats why we think that it might be going out.

We have also triggered it on ISTA/D and the fan will make some small noise and then go full speed but we are unable to check low speed.

Also the coolant tube near the radiator cap seems too hard to press when car is hot. Is this normal since it is a pressurized system ?

Any help would be appreciated. Thanks

Can't help with why the expansion tank cracked (although I understand that is a very common issues on petrol X5 cars related to age and heat) but I CAN tell you the aux. fan operation looks totally normal. The twitching at start up is part of the fan start diagnostics and they all do it.

*edit* and yes, activating the fan via INPA or ISTA/D will cause it to go through the start up cycle, then run up to full speed. There doesn't seems to be a way (or a need) to test it at lower speeds.

Thanks wpoll, i was also told that the expansion tank is common to crack. But we were investigating relating the auxiliary fan because on freeway ride during the middle of a hot day sometimes the AC would be very cold and then not so cold. And having in mind that the fan speed is reduced with the increase of speed. Thats why i wanted to try lower speed fan test.

I doubt the aux fan would be running at all when you are driving at highway speeds. It's only activated when the car is still in traffic or moving slowly, to increase cooling when the airflow through the radiator and heat exchanger is zero or low.

Variation in A/C performance at highway speeds may well be an issue with the gas charge or compressor performance etc. but not likely anything to do with the aux. fan.

Interesting- what you are saying is the opposite of what is more common. You say that the AC is not cold while driving at freeway/highway speeds.

It's usually the exact opposite with a failed aux fan. While around town or slow traffic, the condenser is not flowing enough air through it (because the aux fan is not working). Typically the AC works fine at highway speed because, well, you're moving at speed and air is flowing through both the radiator and AC condenser.

The expansion tank is a weak point on the car, the expansion tank and aux fan both fail around the same mileage, along with a myriad of other parts.

If you end up doing the aux fan, the front bumper will have to be removed. Here's a video DIY I posted up last year when we did our fan. Funny enough, I replaced the expansion tank shortly after as it had a hairline crack.

E53 front bumper removal:

https://youtu.be/QkPxUSSa0L8

E53 aux fan removal and replacement:

https://www.youtube.com/watch?v=N_K0KPHsteA

Thanks richardb for the reply and the videos. They were very detailed and i will need them one day but i hope not too soon :P

I think that it was just the expansion tank failing since is common issue. After replacing it and also the water pump and radiator cap as precaution the car seems ok. ( i also wanted to replace thermostat but they didn't have in stock and i didnt want to buy aftermarket. )

The AC is still not that cold only on very hot days and on freeway ride but this is occasionally . I think i will have to go to ac ac shop to check the gas level.

Thanks