Auxiliary fan appears dead - simple diagnostics - 2006 3.0
 

before anyone says so, yes I have used the search feature & I have a decent idea of how the auxiliary/condenser fan is controlled.

Background:
My wife is the primary driver of our X5. A week or so ago, my wife reported a loud "pop" and immediate full coolant loss/steam/etc., pulled over & X5 comes home on a flatbed. Expansion tank had split open (apparently in a dramatic way) and I replaced it (along w/ the broken thermostat that sits in the base of it). A couple days ago, the temperature rises above normal, she pulls over, gets a ride home. I check it later (suspecting I had not adequately bled air from the system), topped the coolant & we drove home (and have subsequently driven it a number of times) with no engine temp issues.

But, apparently starting around the point of the exploded expansion tank, the AC consistently fails to blow cold when the X5 is not in motion. In motion, it cools terrifically. Very quickly, I noted the front/auxiliary/condenser fan is not coming on when the vehicle is at rest (as I suspected it should).


I have found no blown fuses related to the AC & I checked the 5 50A fuses & they all look good. I have a simple OBD scanner & the iphone Dashcommand app & this very crude diagnostic setup does not detect a fan failure (I understand the fan should be powered up briefly at startup as a diagnostic check & return a failure code if a problem is detected)

So, my question(s):

How much of a factor is this front fan for managing engine coolant temperature? Would it failing be a logical precipitant to the initial problem we had with the tank exploding (though, hey, it's a 10 year old unit, I understand age itself is a good factor!).

As I understand it, this fan is operated at infinitely variable speed using a grounding signal from the ECU. I also saw a thread here that referenced a mechanic using a simple test light to verify a signal going to a fan (albeit on a Chrysler minivan) as an analogous setup. So, is there a way for "mere mortals" with fairly good mechanical skills but not a high end diagnostic computer to check the fan (or the signal to the fan...which I would think would return the same info, right?) either with some type of test light/meter setup or tricking a temp sensor somewhere that should turn the fan on?

Again, I realize this may all be info that's woven into threads here. I've gotten some of it & saw some comments about shorting a high pressure AC switch or disconnecting the lower radiator hose sensor to trigger the fan. Attaching any test equipment to the ECU without being extremely clear what it would be doing seemed like an exceptionally bad idea, so I've not done that. Creating a 'test' signal (either triggering the ECU, or wiring directly to the fan motor pigtail) to engage the fan would seem do-able, but I'm not sure where to begin.

If you've read this far & have any helpful info, access (or a URL) for the proper section of an Electrical Diagnostic Manual for the E53, thank you in advance! We have loved the X5, but it may be pressing my rather informal "3 strikes & you're out as a family car" policy...even though it's registering 164K miles and 10 years old and if I'm honest, I can't complain too much about some of the recent repairs I've had to give it.

Chris G
Knoxville TN

If you get AC on the highway, but not in stop and go traffic? Then it's the aux fan.

If you could afford to buy a BMW you should be able to buy BMW Scanner 1.4 and the diagnostic cable. Any old computer running XP should be useful. BMW Scanner 1.4 is fairly easy to install and a scan is very easy to perform. A bad fan will show up in the DME module.

Perhaps a local Xoutposter can scan your X. I scan the X for a local poster and informed him that he had a bad aux fan. He found an indy to replace the fan and his ac was cold again.

A bit of assumption there....maybe I can't afford the X5! ;) But nonetheless, I'd assume I can afford whatever, I would simply rather not spend money for a fan of its something simple. (Also, it is questionable whether we are keeping the X5 much longer, so that is a consideration for 'special tool' investments). Does it cost more than an hour of shop time for a diagnostic?

EDIT: looks quite inexpensive....should be basic software with the Amazon or EBay sold Scanner 1.4 be adequate ?

Anyway, thanks and yes the AC works perfection when the vehicle is in motion but blows warm when stopped. Replacing the fan looks simple enough to me, so I d guess of a scan is the only option then I'll look into it.

Any feedback on whether the fan failure is a likely component in overheating? Seems it would be.
Thank you!

Here's my thread and posts on why my Aux Fan failed.

http://www.xoutpost.com/bmw-sav-foru...fan-fault.html

Here's the thread in which I scanned a fellow outposter X and determine for him that he needed to replace the aux fan

http://www.xoutpost.com/bmw-sav-foru...-suddenly.html

If you can't afford 26 bucks to find out if the aux fan is bad, your wife needs to look at alternative transportation like the City buses or a bike.

https://www.amazon.com/iSaddle-Scann...MW+scanner+1.4

She would probably be happier driving a later model KIA with a working AC system instead of an old BMW X5 with a non working AC system.

Thanks, and yes after I wrote the initial post I saw that we're talking about well under an hour of shop time versus a multi hundred dollar rig.

Sadly perhaps (actually I dig the idea because it also makes an ideal road trip vehicle for bicycle racing), the X5 is likely to get replaced with some sort of Japanese minivan. That said the X5 will either go to my daughter or be sold if that is the case and either way I want it to be right. I typically drive 1970s Fiats so I really don't know what air-conditioning is ! (Sorta kidding ). Wife & kids need cars that work like good appliances .

I have a good friend who did independent work for a long time, and I always borrowed his scanning equipment for anything serious. Lately however the equipment got damaged and he is focusing on restoring vintage Land Rovers so there are no computers to scan

None of my Lotuses have AC and the only reason why I brought the PORSCHE 911 Targa was because it has AC. The G35 is what we normally use since it has AC and it's almost like a Lotus in the fact that it's a front mid engine car and handle just as nice if not better then the Lotuses.

Front bumper cover will have to be removed in order to replace the aux fan, don't buy one of those cheap fans on eBay or Amazon, either get an OE from BMW or get a Behr fan. Stay away from the Dorman fans.

if you have access to an old laptop (WinXP)you can get a copy of INPA for nix and one of these cheap: -

Car Diagnostic :: By Product Type :: INPA & Ediabas :: BMW INPA / Ediabas KK USB Interface - one-stop-electronics.com ; DCAN Interface, Ethernet to OBD2 Cable, KK USB Interface, ADS USB Interface

With INPA you can read codes, read real-time data and activate functions. You can also clear codes too, after you've resolved the issue present.

I just used INPA last weekend to activate my aux. fan - it doesn't get much use in the winter so I run it for a bit every now and then, just because! ;)

We've had some pretttty hot temps this year. Some even recordbreaking days....
Don't know how long this has been going on but turns out our aux fan is dead....

At least the compressor is still fine.

Indy pulled up the code.
Then did the usual (fuse, etc).

Wifey never noticed the car was ~not cool~ ever except for one instance while parked and had the car running, she thought it was mild, but it was just due to the heatsoak...

Had Indy checked pressure. Pressures just fine....so it's just a fan replacement.

Go figure. Just short of coincidence that the X is at the dealer and he pulled up the codes, wifey never noticed the X not producing AC. Granted, since day 1, AC is not uber cold like some other makes.....

If the wifey did a lot of highway driving, the air movement across the condenser is enough to cool the refrigerant that the AC will appear to be working. It is only in stop and go traffic that you will notice that the AC is not working. Not enough air movement across the condenser so the high side will become elevated and once that happens, the high-pressure cutoff switch will kick in to stop the compressor from compressing any more refrigerant. At that point the AC is DEAD.

Having the car at the shop is a nuisance. Household has 1 car in the mix.

While at the shop, would one errrr on having indy evac and the fill back to weight.

Indy says AC blows cold.
I don't drive it much, but when I have, AC seemed fine to me.