E39 Blower not working

[Chedley]

....
I'm not a fan of just shooting the parts cannon at problems.... So is there a way I can test the IHKA to determine that it is the actual problem.

And it's not the FSU... As everything works with the relay bypassed.

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Do you have INPA set up ?
I think INPA can read, test, and diagnose the IHKA module. Also, a bad FSU would throw an error code at INPA. So, it worth checking it out.

[jharmon718]

Do you have INPA set up ?
I think INPA can read, test, and diagnose the IHKA module. Also, a bad FSU would throw an error code at INPA. So, it worth checking it out.

I have PA Soft set up. Only error code in the IHKA is for the AUC Sensor by the radiator

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[ross1]

You mentioned in a PM that no power to the coil winding of the K4 relay and there WAS a ground signal coming from the controls. Right?
Perhaps someone here can tell us what circuit/fuse serves the winding* of the K4 relay. Without power there the relay will never close, regardless of command.
* I've looked at Bentley wiring diagrams and cannot see what serves it.

[jharmon718]

You mentioned in a PM that no power to the coil winding of the K4 relay and there WAS a ground signal coming from the controls. Right?
Perhaps someone here can tell us what circuit/fuse serves the winding* of the K4 relay. Without power there the relay will never close, regardless of command.
* I've looked at Bentley wiring diagrams and cannot see what serves it.

Yeah I backprobed the relay and applied power to the switch side of the relay and it was working. So the relay checked out. From what I can see on wiring diagrams the power signal comes directly from the IHKA, there's no break, splice, or fuse in that circuit.

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[ross1]

IHKA applies a GROUND signal to the relay term 85, if no power is present at term 86 the relay will not close.
Please share the diagram indicating power from the IHKA. I could not find the source. If IHKA and no breaks, fuses, etc. then IHKA seems the culprit.

WAIT a minute. On a diagram in the Bentley(pg 640-6) it indicates 12V+ IS applied by IHKA. The terminals are not indicated but typical (DIN?) would be pin 86. Is pin 85 ground, regardless of commands?
Interestingly the relay appears in none of the actual wiring diagrams. Typically the controls send the ground signal, not 12v+
Between this and an Italian wiring nightmare I'm working on I'm confused. Hope I'm not adding to yours, say so if so.
IS term 4 on the FSU seeing ground?

[jharmon718]

IHKA applies a GROUND signal to the relay term 85, if no power is present at term 86 the relay will not close.
Please share the diagram indicating power from the IHKA. I could not find the source. If IHKA and no breaks, fuses, etc. then IHKA seems the culprit.

Ground is at location X10012 (Right side of footwell) power comes from IHKA

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[ross1]

HEY! Yours is '98, right? Bentley says that is IHKR which as indicated on pg 640-9 doesn't use a blower relay, this concurs with my wiring diagrams. Seems they didn't update for later(9/99+up) versions.
Now I'm really confused and about to have a look at my '97 to see if it has the relay.

[jharmon718]

HEY! Yours is '98, right? Bentley says that is IHKR which as indicated on pg 640-9 doesn't use a blower relay, this concurs with my wiring diagrams. Seems they didn't update for later(9/99+up) versions.
Now I'm really confused and about to have a look at my '97 to see if it has the relay.

I have a 07/98 540i that has the relay

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[ross1]

I am going to shut up.
I clearly have bad info here.

[jharmon718]

I am going to shut up.
I clearly have bad info here.

I appreciate you trying to help me! After 08/98 they went to a slightly different system that doesn't utilize the relay

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[jharmon718]

So I tried another IHKA that I pulled at a junkyard and still there blower motor doesn't activate.

Does anyone know how to actually recode the IHKA as this is the only thing I can think of to do?

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[jharmon718]

I checked the wiring from the IHKA to the blower motor relay and I have continuity (~0.1Ω).

I then backprobed the connector at the IHKA and have no power out at the module. I tried this with another IHKA, as stated in a previous reply, and have no power out of that module either.



I tried using INPA on my laptop to check the module but can't get past the main page and I'm not sure why.

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[JimLev]

Have you checked the fuses for the IHKA?
Do you have power coming into the IHKA on the specified pins?

IIRC recoding is just for different parts of the country/world for things like climate, sun load, etc.

[jharmon718]

Have you checked the fuses for the IHKA?
Do you have power coming into the IHKA on the specified pins?

IIRC recoding is just for different parts of the country/world for things like climate, sun load, etc.

With the a fused jumper wire on the blower motor relay everything on the IHKA is functional. There is no fuse for the switching side of the relay only the main power side.

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[Bainmw]

I’m currently having this same problem, replaced the IHKA and blower motor relay and can’t find out why my blower motor isn’t kicking on. The blower motor works, on my old IHKA it would turn on the blower motor, but not blow cold air even though the A/C compressor works and is full. Did you ever find out what was wrong with yours?

[jharmon718]

Nope I have a fused jumper wire where the relay should be so that I have heat and AC. Not getting a switching signal from the IHKA

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[Nahmann]

Nope I have a fused jumper wire where the relay should be so that I have heat and AC. Not getting a switching signal from the IHKA

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wondering if you ever resolved this. have 97 540 and having the same issue

[Coach J]

Yes, the FSU can fail such that no air blows at all; it's happened to me.

Me too !! So when I’m parked no air hot or cold then once I get up to bout 40mph air will come through!!! Is this my fsu or blower motor??