E39 aircon fan auto on/off even when engine is off

[jaleeks23]

dear all,Last night was the first time I saw this happening after owning the E39 for 2yrs. Last night, I arrived home at 7pm+ and parked the car in the porch and never drove since then. I also always open the bonnet to let out the heat whenever I reached home and close the bonnet before going to bed. At about 11.30pm, my friend came to look for me and we were chatting at the gate. As I always reverse park my car in the porch, we were close to my car's bonnet. BTW, the bonnet was closed then. Suddenly, the aircon fan started! It was running at low speed for about 2-3mins, then it switched off itself.Question is1) Is this a "hidden" feature? (I remember reading somewhere in this forum but couldn't find the thread anymore and couldn't determine if it's a problem or feature)2) Is there a reason for the fan to auto on/off? - to test the fan or ventilation for the engine or.....?3) I doubt it's shorting somewhere cause it just auto on and then auto off. (but I will still check with mechanic and aircon fella)Really hope owners and sifus out there can explain this hidden feature or problem. Thank you.

 

[bmw7833]

I never experience this even i also open my bonnet in hot climate. New thing to me..

 

[jaleeks23]

Just read in forums.bimmerforums.com the E39 has this aux ventilation where it circulates air in the cabin. Very cool feature. Anyone knows if this feature is also available in CKD cars in MY? It can be turned off too. Thank you.

 

[affan66]

if the aircond fan is still ON when engine is off, it could be that the aircond gas is low. Another cause could be that the aircond fan itself is nearing end of life.

 

[jaleeks23]

Thanks affan66. Guess will have to monitor for awhile.

 

[initialM]

My E39 aircond fan does not working when on aircond. Check out the price & found out the new ori one cost RM1500. OEM is cheaper but was advice not use it. Plan to mod using aftermarket fan but not sure if its ok. Anyone has change the aircond fan?
If not just opt for use one at RM550:burnout:

P/S: sorry for sharing thread:love:

 

[zank]

Aircon fan running when engine is off is a known problem, if you do search hard enough on this website you will find the answer, basically you need to change the Final Stage Unit (FSU) I think it is around RM200.

http://www.bimmerfest.com/forums/showthread.php?t=143393&highlight=fsu

 

[Vincent Hor]

Bro, the aux fan for E39 & E38 are similar. It should run on 3 speeds instead of two. Try checking the wiring, fuses and relays first. If proven that the fan is bad then I would get a good one from the chop shop. Afterall it would be an original instead of OEM.

My E39 aircond fan does not working when on aircond. Check out the price & found out the new ori one cost RM1500. OEM is cheaper but was advice not use it. Plan to mod using aftermarket fan but not sure if its ok. Anyone has change the aircond fan?
If not just opt for use one at RM550:burnout:

P/S: sorry for sharing thread:love:

 

[James Chun]

I had this problem before on my E39. My Mechanic replace some sensor, cost me RM350 ...no problems untill today, already 3 years...

 

[selfmech]

Hi Jaleeks23,

Not sure which year is yours but there is two types of aux fan for E39. Pre '98 (4 wire connector) and post '98 (3 wire connector). I just replace mine twice as my ori fan bearing worn out so I went and bought a VEMO (made in Germany) where it lasted less than 4 months. Now I installed the ori Seimens fan and is working fine.
A lot of issues with the VEMO fan that cannot read the pulse for the ECU hence the speed becomes abnormal and at times when the engine is off it will run itself like what you have experienced.
Check your fan type. Pre 98 ones can be repaired if the resistor is out whilst the post 98 ones its best to buy the ori.

Rgds.

 

[Vincent Hor]

You are spot on. To differentiate the 2/3 speeds is the number of wires, 3 or 4.

I don't believe in those OEM aux fans, that's why I recommended chop shop. Great savings there.

Hi Jaleeks23,

Not sure which year is yours but there is two types of aux fan for E39. Pre '98 (4 wire connector) and post '98 (3 wire connector). I just replace mine twice as my ori fan bearing worn out so I went and bought a VEMO (made in Germany) where it lasted less than 4 months. Now I installed the ori Seimens fan and is working fine.
A lot of issues with the VEMO fan that cannot read the pulse for the ECU hence the speed becomes abnormal and at times when the engine is off it will run itself like what you have experienced.
Check your fan type. Pre 98 ones can be repaired if the resistor is out whilst the post 98 ones its best to buy the ori.

Rgds.

 

[jaleeks23]

thanks so much guys....
my E39 is 2003, therefore don't think I can change the resistor. I think finally, my aux fan kaput cause just now while driving suddenly no more cold air, reached home and check, fan doesn't turn anymore when I switch on the aircon, aircon blows normal temperature air, not cold air. Will check the FSU (near driver side kick-panel) but I doubt it's that cause my aircon is not running eratic. Will see tmrw the mechanic lor.....sigh.....there goes $$....hopefully can find good one from chop shop...

 

[initialM]

two types of aux fan for E39. Pre '98 (4 wire connector) and post '98 (3 wire connector). I just replace mine twice as my ori fan bearing worn out so I went and bought a VEMO (made in Germany)
Check your fan type. Pre 98 ones can be repaired if the resistor is out whilst the post 98 ones its best to buy the ori.

Rgds.

Bro how much you bought the OEM & ori aircond fan? Mine is 528 CBU yr 97.
If that so how/where to repair if the resistor faulty? Plan to repair 2morrow morning coz mine is not working. Where's yr location in JB. Appreciate if you could sms yr hp no. TQ

013-7235354

 

[Vincent Hor]

InitialM, if it's just the resistor that is faulty, then you mechanic may have spares from those whereby the motor or bearing kaput.

Quote :
Bro how much you bought the OEM & ori aircond fan? Mine is 528 CBU yr 97.
If that so how/where to repair if the resistor faulty? Plan to repair 2morrow morning coz mine is not working. Where's yr location in JB. Appreciate if you could sms yr hp no. TQ

013-7235354

 

[affan66]

there is supposed to be a sensor/switch connected to that fan too. And yes, check the fuse before you go and spend on a new aux fan. I've changed mine before.

Try and recall if the fan was louder before it died today. That's a sign that it is roaring to death...

 

[jaleeks23]

hi all, my aux fan is still working.......so far ok!...
Cud be connection issue but dunno where....

Affan, where is the sensor you are referring to?

 

[affan66]

if i recall correctly, it is a fan switch. Next to the fan itself.
The resistor sensor that the guys are talking about I believe is in the cabin but I have yet to hear of this problem on the E39 but only on E46ers..

 

[selfmech]

hi all, my aux fan is still working.......so far ok!...
Cud be connection issue but dunno where....

Affan, where is the sensor you are referring to?

If I am not mistaken, two wires supply power to the fan whilst the other small one send the speed signal. Believe processing comes from the ECU various inputs like the coolant temperature sensor and air con pressure sensor to determine the speed the fan should run. I have not seen any controller unit under the glove box but only a huge fuse.

Rgds.

 

[jaleeks23]

I think I found the wire connector for the fan, it's located just at the side of the driver's headlamp, saw three wires in the connector. Another thing which I've noticed is that when I turn on the aircon, the compressor starts, but the fan "hesitates" to turn when engine's cold. It turns a bit, then stops, then turns a bit, then stops....then turns...
After that, it looks ok...when engine's hot, when I turn on the aircon, the aux fan starts with a slight delay...

 

[bimmer73]

Jaleeks it is normal my brand new fan also does that......My advise is to go for Ori brand new fan cause it it is associated with the cooling system...rest assured not worries of weather the fan is turning when it suppose to