Fan issue

[chasbush]

I'm restoring a '97 740i and have a question. In the dash a fan keeps running no matter if car is turned off or whatever. This kills the battery over time so its a semi-major problem. I read somewhere that there is a "module" that can malfunction and cause this. Can anyone enlighten me on how to fix this? Thanks muchly.

[shogun]

Moved to E38 forum from 7 general

[Nitchfam]

Your blower motor resistor/fan assembly under the dash has failed. I recently had this problem. It requires removing the dash. Not a hard job, just very time consuming. Used part can be had for a reasonable price, just make sure it works and blows like new before reinstalling dash.

[Mayorchuck]

Here is a thread I made up some years back. For your model year, be sure to note the info and links on the K4 relay. It could be the resistor that sits on the blower motor but it usually just kills the power to the blower, unlike other models where it causes it to run non stop. If you have to pull the dash, you will find DIY's within the thread below. I've done this several times and, as stated, it's not a difficult DIY.

https://www.bimmerforums.com/forum/s...eral-HVAC-info

[chasbush]

can someone tell me what "FSU module" is and what it does? I hear a small fan running in dash that I can't seem to shut off. Any ideas to fix? Would replacing fan and resistor unit do it? Its a pain 'cause I'm forced to keep a trickle charger on the car so the battery doesn't die. Thnx!

[chemmech]

the small fan seems like it would be the climate control module air sampling fan not controlled by the FSU module main blower resistor pack (final stage unit module), doesn't the small fan come on to sample the interior air temps to control the ventilation system of outdoor air flow into the car when it is off as well as key on position or the car is running not sure... maybe the climate control module is glitching if it has the small fan running constantly..... probably old capacitors need to get replaced if it is glitching.....

[Nitchfam]

You made a thread about this already a few days ago and a solution was offered there I had thought. You need to replace the whole blower motor and resistor as one piece...problem solved..

[Mayorchuck]

The fan in the IHKA is activated when the car is 'awake'. The fan sits on a magnet and is activated by on of the bus systems. As stated, it has nothing to do with the blower motor and resistor. When you open your door or use the key fob, the General Module 'wakes up' the car. Once you turn off and leave the car, all systems shut down after 16 minutes, including the bus that would cause the IHKA fan to run. If the car is not going to sleep, you will need to find out why. If you sit in your car for 16 minutes after shutting it off, without opening the door, the fan should stop and the P light on the gear selector should go out. If this does not happen, you need to find out why. Timm has a good write up on his site on battery drain. It could be the climate control module (IHKA) or something else on that bus.

https://www.meeknet.co.uk/E38/E38_Battery_Drain.htm

[BimmerFlyer]

Good advise from MC.... however, if the General Module is being kept awake by one of the busses it communicates with, the trouble shooting gets a lot harder.....and the General module itself can get a little “loopy” with old age and start doing some strange stuff as the electronics age... fun fun fun...
Pete

[chasbush]

so, I'm restoring a '97 e38 740i and have an issue. There is a small fan (I'm thinking not main blower fan) that stays on constantly, even when car is shut down, fan speed at zero, etc. Hours later, still on. Of course, it kills battery. Anyone know how to fix or where fuse is located? Appreciate it.

[SwallownAmazon]

This is the THIRD time you have asked this question - did you bother to read the answers you were provided with by other very experienced owners?

[alexisonfire]

This is the THIRD time you have asked this question - did you bother to read the answers you were provided with by other very experienced owners?

+1

[Mayorchuck]

Threads merged.

[alexisonfire]

the small fan seems like it would be the climate control module air sampling fan not controlled by the FSU module main blower resistor pack (final stage unit module), doesn't the small fan come on to sample the interior air temps to control the ventilation system of outdoor air flow into the car when it is off as well as key on position or the car is running not sure... maybe the climate control module is glitching if it has the small fan running constantly..... probably old capacitors need to get replaced if it is glitching.....

Oh my bad then I was immediately thinking blower motor / resistor under the dash but read it again and yeah then it sounds like the little fan in the IHKA climate control unit.