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Discussion Starter · #1 ·
Hey everyone, this is my first post here so if i am asking something which has been answered before please direct me to it because all my search came to a dead end.
i have a 2004 545i, only 94k kms driven, everything was running smooth and all of a sudden my ac blower speed went really low, after a while of driving it became normal again. ( this was two days ago)
but now the blower speed is stuck at low, no matter what i do it stays there, i have tried auto/max/manual everything but the blower speed won't increase.
there are no codes in the system and if i do a test of 100% blower speed with OBD scanner, it works perfectly.
but as soon as i start the car and turn on the AC, air speed is very low and stays there.
any help would be appreciated.
 

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Discussion Starter · #3 ·

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if i do a test of 100% blower speed with OBD scanner, it works perfectly.
but as soon as i start the car and turn on the AC, air speed is very low and stays there.
any help would be appreciated.
Can you start car and still use OBD scanner to control blower? IHKA is the module that controls these systems. This is a guess, I'll let you use this guess to research further, but the Blower Dial communicates with IHKA module, and then IHKA module sends signal to blower to control it. So, if other systems that are controlled by your IHKA module seem to be working, and the module is showing no codes, then maybe your Dial/Control has a problem, but the IHKA might throw a code if it cant see it. Or, maybe it does see it, and thinks all it wants is LOW, thus no codes.

Try your rear window defrosters and see if they are working, and anything else related to climate control or the IHKA module controls. If all is working, except blower speed, suspect the dash board dial. Maybe you can get lucky, take it out and blow some air in there to get some dirt out and it will start working again. its easy to remove, I did a photo shoot and posted photos on the board here recently on what needs to come off and what is behind everything.

 

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Discussion Starter · #5 ·
Can you start car and still use OBD scanner to control blower? IHKA is the module that controls these systems. This is a guess, I'll let you use this guess to research further, but the Blower Dial communicates with IHKA module, and then IHKA module sends signal to blower to control it. So, if other systems that are controlled by your IHKA module seem to be working, and the module is showing no codes, then maybe your Dial/Control has a problem, but the IHKA might throw a code if it cant see it. Or, maybe it does see it, and thinks all it wants is LOW, thus no codes.

Try your rear window defrosters and see if they are working, and anything else related to climate control or the IHKA module controls. If all is working, except blower speed, suspect the dash board dial. Maybe you can get lucky, take it out and blow some air in there to get some dirt out and it will start working again. its easy to remove, I did a photo shoot and posted photos on the board here recently on what needs to come off and what is behind everything.

if i turn on the front defogger the blower works at full speed and i can control it with the dial.
I think i should try replacing the blower regulator. The normal temperature here during the day is around 40-43°c so the car is pretty much non drivable with the blower stuck at the minimum speed
 

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One other thing to consider is your battery health. When voltage is dropping your BMW may be trying to conserve power where it can. Its known for BMW systems to drip vent speeds down to minimal for this reason. It’s possible that your scanner is bypassing the conservation. How old is your battery and have you encountered any other issues? If it were me I would be throwing my BMW on a battery charger, letting it charge full, and then testing the blower while fully charged just to rule it out for free. When I suspected my blower or regulator was bad I decided to replace the entire blower. It came with a new regulator installed. For me (different model), I replaced the blower and regulator for $90 more than it would cost to replace just the regulator.


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^^^^^ What B said. Great idea. Excellent theory.
 

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Discussion Starter · #8 ·
One other thing to consider is your battery health. When voltage is dropping your BMW may be trying to conserve power where it can. Its known for BMW systems to drip vent speeds down to minimal for this reason. It’s possible that your scanner is bypassing the conservation. How old is your battery and have you encountered any other issues? If it were me I would be throwing my BMW on a battery charger, letting it charge full, and then testing the blower while fully charged just to rule it out for free. When I suspected my blower or regulator was bad I decided to replace the entire blower. It came with a new regulator installed. For me (different model), I replaced the blower and regulator for $90 more than it would cost to replace just the regulator.


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My battery is new, replaced and registered a month back, voltage are fine too.
I found a used resistor lying around with a friend, installed that yesterday and the issue still remains, but surprisingly the blower speed is now stuck at a little higher speed than it was on the old resistor.
If i use the front defogger, it works on full speed and can be controlled with the dial too. Weird issue.
Thinking to import a complete blower+resistor and replace the whole thing.
This is really frustrating.
 

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Discussion Starter · #9 ·
One other thing to consider is your battery health. When voltage is dropping your BMW may be trying to conserve power where it can. Its known for BMW systems to drip vent speeds down to minimal for this reason. It’s possible that your scanner is bypassing the conservation. How old is your battery and have you encountered any other issues? If it were me I would be throwing my BMW on a battery charger, letting it charge full, and then testing the blower while fully charged just to rule it out for free. When I suspected my blower or regulator was bad I decided to replace the entire blower. It came with a new regulator installed. For me (different model), I replaced the blower and regulator for $90 more than it would cost to replace just the regulator.


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btw where did you get the blower and regulator for 90$? the behr regulator only from pelican parts is of 105$
 

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btw where did you get the blower and regulator for 90$? the behr regulator only from pelican parts is of 105$
I didn’t buy it for $90. There was a $90 difference between getting just the regulator compared to the blower + regulator.


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