Ihka unit Problem solved?

[araber95]

Hallo to everyone. I had Problem before with the ihka. The Problem is that the air conditioner doesnt want to make Cold. First I checked the System it was okay,after i noticed that the heater valves were dead so I installed e39 heater valves and on the end still no Cold in summer. So i have tried friends unit from working Car and voala it worked! So now I wanted before buying other unit to Check the Old one and... Check this. The Temp Sensor was with a lot of dust A LOT. Could this be the Problem? The Electronic plate and condensators are Looking good.

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[shogun]

That is most probably the problem, broken temperature sensor. On my website I have pics of a broken temperature sensor, it had cracks and the temperature was always changing, no matter what the settibg was.
See fixes>>climate control>> Room temperature thermistor http://twrite.org/shogunnew/topmenu.html
There is a small motor with a fan that passes cabin air over this thermistor -- so with age the thermistor can become incredibly dirty. Carefully clean it with brake cleaner. Check that the solder joints are not cracked.
Room temperature thermistor
Glass bead NTC G540 thermistor,10k
RS Stock No. 528-8558
Manufacturer EPCOS
Manufacturers Part No. B57540G0103J

resistance readings are also shown on my website

[zubbie]

Thanks for that Shogun.

As one of the few here who own and maintain an IHKA system it's great to have your knowledge as a resource here.

[shogun]

here more pics of AC control innards, takes some seconds as recovered with wayback machine http://web.archive.org/web/200206091...w.com/ac_cont/

[araber95]

ok so I already changed the Ihka unit and we got cold air as well..but we got 2 more problems .On the left side the air flow is less (maybe 1/2 )than the right side could this be step motor ? and Second the aux fan doesn't work(it wasn't working also before the change) could this be relays -my motor is m51d25 (1992 yr touring)? where they sit and how they look.First I checked the fuses and they looked fine. ...Ahh.. This ihka kills me pls guys help .

[araber95]

Any advice?

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[BleedsBlue]

Test aux fan first: http://www.nmia.com/~dgnrg/page_20.htm

For airflow problem on left (driver) side, is it half speed from all vents (top, middle, bottom, etc)? Could be an issue in the control unit dial, or if it is one vent then likely stepper motor.

[Smith Jason]

Could be a broken stepper motor mount also. Quite common apparently.

[shogun]

If the airflow is different: I had that on my E32, the stepper motor bracket on the driver side was not strong enough anymore and slipped out of position, I fixed it with a zip tie, so far so good. Better fixes here

http://www.bimmerboard.com/forums/posts/200205/
or broken flap bracket http://www.bimmernut.com/forum/showt...light=cold+air

[araber95]

Ok so I checked the relay on low speed and it was ok. So at the end I decided to change the resistor I removed it and on it there isnt any sign (from the years) what resistor should i buy?

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[araber95]

Here it is

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[shogun]

http://bmwfans.info/parts-catalog/E3...tional_blower/

repair kit reistor 64121388069 MAGNA or resistor 17401373177 BOSCH or from Beru, here you can buy in Germany https://www.autoteiledirekt.de/oenum...401373177.html

[araber95]

Does matter which one I will choose?

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[araber95]

My Fan is the plastic one. Looks like that one (not my pic)

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[shogun]

all fans have plastic blades, use your car VIN and check on www.realoem.com the part number and buy that part number. The items is under heating/aircon

[araber95]

Ok so Im gonna buy the Bosch resistor, but now one guy told me to put it in a better place where will get enough cool air and wont burn that fast, any advice guys from you?

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[shogun]

Install it at the same place, no problem for the next 10-15 years, there it get's cooled as the air goes into the radiator, and the place is quite good protected against water.

[araber95]

Thanks a lot Shogun

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[shogun]

BTW: you could also buy a complete new no name auxiliary fan for less than $100.
If the present aux fan is already 25 years old, then better buy a complete new one which comes with a new resistor.
Most old aux fan die when the magnets inside the motor get lose and block the motor, they are glued on and over the years they get lose and block the aux fan, fuse usually blows, but I have seen also some cars where the amp was not enough to immy blow the fuse and the fuse box melted and the wires.

[araber95]

Eh I checked all my fuses are with ampers exactly what they need to be. Now you scared me


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[shogun]

In such a case, we made a repair guide to open the motor and re-glue the magnets here on the German E34 forum https://forum.e34.de/thread.php?thre...=zusatzluefter
with date 17.08.2015 I also posted the sizes of the carbon brushes when I disassembled an aux fan made 1988 from my E32 750 just for fun to check all the details. But I bought a new col. aux fan from an online shop, made in Taiwan, works now 3 years without any problem.

[araber95]

I ordered already the original Bosch resistor. I checked the Fan directly with + cabel and it works smoothly so at this moment i wont do anything Else. Thanks a lot Again Shogun
Greetings from Bulgaria

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