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RaduG86

BMW E39 Heating&Ventilation Problem

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Hello! I've recently started experiencing some problems regarding the ventilation in my 1996 BMW 520i E39. The blower won't work at any speed, and when it used to work, whenever I would turn the engine off, the IHKA panel would light up again and the blower would start for aboult haf a second and then it would turn off. I've checked all the fuses and they are all good. After reading some more, I've decided to buy a brand new FSU, but that didn't solve the problem either. The blower itself has been checked today and it works, but I can't control the speed through the IHKA. The battery has been changed today with a new 75Ah model. Also, before I changed the battery, whenever I used to plug or unplug the FSU (at least that's when it happened to me), the battery would drain. What else is there to check? Thanks in advance!

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Which FSU did you buy, they need to be either the likes of the Meyle one that’s c£35 on eBay, or OEM BMW. The cheap eBay ones needed to be avoided.

 

Also your battery needs to be bigger ideally, the likes of the Yuasa 019 or Bosch S4 019 at a minimum. These cars like a solid battery to keep them going.

 

Re your heater issues, it could be an issue with the HVAC control panel or the heater valve in the engine bay (or both), so look to them also as possible issues

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Hi, thanks for the advice. I have tried with 2 FSUs, one being Hella (BEHR) and the other one Febi Bilstein. Neither of them works. Also, I've checked for codes using INPA, and I had a code related to the auxiliary water pump. Something like:

 

21      Auxiliary water pump

 

Short circuit to ground

Error present

 

Errorcode: 15 42 0C 48 3F 3E AE 00 10 03 7E

 

 

I'm starting to think that the problem is caused by something like a loose ground cable somewhere. Also, I've checked the relay behind the glovebox and it seems everything is ok. I've checked the 50A F75 and that is ok as well (my car doesn't seem to have the 40A F76 at all). The following days I will try using the HVAC panel from another car to see if that helps (does it need to be coded or something? if yes, how?). If that won't solve it, I think I will remove the passenger seat and check the grounds under the RH carpet. Thanks again!

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Hi,

I now have a heating & ventilation problem. The HVAC control panel is not illuminating, also fuse number 9 is blown. There is plenty of heat though. Would this be the FSU?

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1 hour ago, davidw53 said:

Hi,

I now have a heating & ventilation problem. The HVAC control panel is not illuminating, also fuse number 9 is blown. There is plenty of heat though. Would this be the FSU?

 

It can be; but if the HVAC control panel isn't illuminating, I'd say that's failed also

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