[Kokolin]

Hi everyone, I hope you can help me because everyone is baffled by this!

I have a 2006 e92 335i with an n54(if that matters at all).
It has developed a really weird heater fan issue a few months ago and I don't know how to fix it, and it's getting urgent since it's raining all the time and frost will become a problem rather soon.

The fan/resistor died, I ordered new ones to change out but in the meantime, BMW sent out a letter about a safety recall(something to do with fan wires melting and causing a fire)-so the car went into BMW to get the safety recall work done.

Once BMW gave me the car back, I changed the FSR and fan itself in hopes of that fixing the issue but it didn't and here I am months later, scratching my head.
The fan works with the key in the ignition slot and ignition turned ON, but the second I switch the actual engine ON, the fan stops working.
I have been to an auto electrician, who said the wires, fan and FSR are fine, and he believes it could be the climate control panel shorting out-so I bought a new one and changed it out, nothing changed.

TLDR: Heater fan(regardless of setting or AC) works with ignition ON, but shuts off when the engine starts and won't come back on. The control panel works.

Any help and ideas would be appreciated, thank you!

[jsunma]

A bit of a shot in the dark, but do you still have the parts you removed, and if so, can you re-install those (especially since they don't appear to have been faulty) and see if the problem persists?

My guess is that you introduced an incompatibility between the revised/altered harness that BMW installed via the recall and the new parts you installed after the fact.

If your problem resolves with the installation of the older parts, then you can either just leave it that way or investigate further to see what the difference is between what you installed and the original part. I'm thinking that the connector is different for the new fan and resistor than the older version.

[Kokolin]

The recall only changed a wire, not the harness or the connection/pinout as far as I know-everything seems to fit fine.

I will have a look though, might still have the original parts laying about.

Auto electrician seems to think there's a short somewhere when the engine is on though

[jsunma]

Sorry, I now see where you said that the fan was broken before you took it in for the recall. I should have read more carefully.

Originally Posted by Kokolin

The fan/resistor died, I ordered new ones to change out but in the meantime, BMW sent out a letter about a safety recall(something to do with fan wires melting and causing a fire)-so the car went into BMW to get the safety recall work done.

I guess the confusing thing to me is that the dealer did the recall work (I had it done on mine too) on a car that had a dead fan? They never mentioned that your fan wasn't working? I don't even know how they could test their work if the fan itself wasn't functional. (yeah, I know...dealer...)

[Kokolin]

Originally Posted by jsunma

Sorry, I now see where you said that the fan was broken before you took it in for the recall. I should have read more carefully.



I guess the confusing thing to me is that the dealer did the recall work (I had it done on mine too) on a car that had a dead fan? They never mentioned that your fan wasn't working? I don't even know how they could test their work if the fan itself wasn't functional. (yeah, I know...dealer...)

No worries, I appreciate any help, anything that'll help me save £££, because electricians are stupid expensive and I can't drive in winter without a fan, it's just not possible

[NZE90]

Have you read the fault codes in the vehicle? That would be a big help.

Also what is the condition of your battery? How old? What is the battery voltage when resting? And with the engine running?

[Kokolin]

Originally Posted by NZE90

Have you read the fault codes in the vehicle? That would be a big help.

Also what is the condition of your battery? How old? What is the battery voltage when resting? And with the engine running?

I don't know how old the battery is, its condition or voltages as I don't have the tools-I did take it to a local garage to get the battery health checked and they said the battery is healthy

I've read fault codes with MHD which displayed no codes as well as Bimmerlink which throws a couple of codes, but as far as I can tell, none relate to the fan or anything related to it

I'll post the codes tomorrow when I go to the car.

[Canuck335]

When you turn on the ignition, is that exactly when the fan stops?
There is a relay that activates to turn off some accessories such as the fan, defroster, etc so the starter has full battery current available. I suspect it’s something in that circuit that’s sticking and cutting power to the fan.

[Kokolin]

Originally Posted by Canuck335

When you turn on the ignition, is that exactly when the fan stops?
There is a relay that activates to turn off some accessories such as the fan, defroster, etc so the starter has full battery current available. I suspect it’s something in that circuit that’s sticking and cutting power to the fan.

No. I put in the key, press the start button(without holding the brake, so engine isn't on but ignition and electricals are on) and the fan will work until battery dies.
If I hold the brake and press the start button again to turn on the engine, the fan will stop and will not come back on until I switch the engine off.

I hope that makes sense.

Car's going to an auto electrician on Monday, hopefully that'll resolve this issue.