Read the IHKA trouble codes using INPA, BMW Scanner 1.4, etc.

 

Before you decide to go cowboy on the car, try a battery reset. Takes only 5 active min. and 1/2 hr. waiting time.

Lower the drivers window and take the key out of the car, put it in your pocket. Open the trunk and manually close the trunk latch. Remove the cover off of the battery and disconnect the neg battery cable. Cover the neg post with a good rag. (Battery cables love to return back) Take a jumper wire and connect the now disconnected neg battery cable to the positive cable. (Don't worry, as long as the neg cable is off the post all is good.) Wait a half an hour.

Remove the jumper wire, remove rag and reconnect the neg cable to the battery. Unlatch the closed trunk latch. Start the car and let it run for a moment or two, then try the HVAC system. See if normal function returns?

 

A likely culprit is the FSR (final stage resistor). Very common failure point. My last e46 had it happen, similar characteristics as what you’re seeing. My current e46 is starting to do the same. Nasty place to get at to replace it though under the dash.

 

A bad FSR won't cause the settings on the IHKA to change.

I'd do the reset that MrMCar is suggesting and see if that helps before you start throwing parts at the car.
Definitely get INPA.

 

I thought I would try a simple replacement of the FSR since the jumpy fan speed seems to get resolved by this often.

In the spirit of "No vehicle repair shall go unpunished", the climate control will just shut completely off.

Are there any follow-up procedures that need to be done after replacing the FSR? I did not disconnect the battery, probably should have...

 

So by connecting the two cables together you bleed down any residual voltage (capacitance) inside any control unit that has such. Sometimes this works, tantamount to hitting that small hidden reset button on some small electronic devices.

The reason you close the trunk latch is to remove the draw that the trunk lamp pulls. Also prevents you from closing the trunk with the battery disconnected. Sometimes folks find out too late that the trunk lock doesn't work with the key inserted into the lock, as most just unlock either via the button inside the car or the one on the key. Albeit with the battery disconnected, that naturally doesn't work.

 

As a precursor, I did scan the car with the ECS Schwaben scanner: ECS Schwaben Scanner Tool Review

It did not find any faults with the IHKA and I think the other HVAC system it scanned was the IRKA?

No codes for either...

 

@Bali was kind enough to step me through INPA. After he updated my DME and EGS from their original 2002 files, we looked at the IHKA.

The screen kept flickering like there was a break in communication from the IHKA. Finally we got an error in INPA. His assessment is that my IHKA has a power supply issue, and needs to be replaced. Anyone know where the best place to buy a used IHKA would be? Or better yet, can I send mine in somewhere to be rebuilt/repaired?

 

Any U-pick wrecking yards around you? You can get that out with not much more that a standard and a phillips head screwdriver.

 

Also check ebay.

Pardon Our Interruption...

 

So, anyone who is experiencing this issue and who has a pre-LCI car with a BlueBus installed: It's probably the BlueBus.

As part of the lighting features, I have to request the dimmer and LWR status from the LSZ (otherwise I will alter the dimmer state in the car and things will be annoying). I had been doing this every time the LSZ sent the dimmer status along (usually after the dimmer pot has been altered, or 58G [back-lighting] is activated), but as it turns out, the LSZ issues the dimmer status along with the response to the I/O status query. This results in a LOT of I-Bus traffic with the dimmer state. I believe the older IHKA has a software bug that is causing something to over/under run in the code and thus error out.

Thanks!
-Ted

 

Thanks Ted, I will try the BlueBus update before I do anything else with my IHKA.
Appreciate your rapid response!

 

Driving the e46 w/o the BlueBus installed - no glitches.

Now I wonder if that FSR really needed to be replaced!

At least I got to learn how to do that.

I did see that it was not the original FSR - date looks like a 2004 unit:

 

Updating the BlueBus to 1.1.15 seemed to fix the glitching where the IHKA would re-start randomly.

 

I thought I better check fuses - I checked 23, 28 and 62 - they all measured continuity (good).

Any other fuses I should check?

 

My favorite video on removing the IHKA - these guys are awesome. It happens just like they said, the small plug is difficult.

I think they probably went out and listened to some techno after this:

 

Compare of the newer style IHKA (on bottom) vs older style on top:

When I pulled my old-style, I blew out the fan and vent with some compressed air - there was definitely some dust in there.

 

More compare pictures of the newer, smaller IHKA vs older:

 

So to summarize for any future searchers...

After working under the intake (for ~1 month) I attempted to bleed cooling system w/ heat full on. Climate control would turn off randomly.

Replace FSR - climate control still turns off randomly.

Try battery reset - climate control still turns off randomly.

Update firmware in BlueBus - this fixes the climate control turning off randomly.

A/C feels weak - then I realize heat is coming out the floor vents.

Replace IHKA - heat is still coming out the floor vents.

Replace heater valve - this fixes heat coming out the floor vents.

Glad I am now able to turn off the heat in November!

 

This car does the goofiest stuff...
I went out to check fuses. When I first put the key in the ON position, no IHKA lights.
I checked fuse 62 & 63 (the 7.5A fuses), they are both good.
Put the key to ON again, and the IHKA lights up!
Hmm...

 

Got a chance to put a few miles on the e46 yesterday, IHKA behaved.
It was warm/hot (temp read @ 100F) and I ran the IHKA in full Auto mode.