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Discussion Starter #1
Hello all,

As the weather is warming up here Ive been experiencing an issue with my IHKA climate control. When on cool setting the fan only works with the switch all the way to the right (on the 0 detent) When I switch to anything in the middle of the range, the fan shuts down and all the auto functions shut down. If i swing it all the way round to max speed, the fan kicks back in but the temperature goes to hot, again no auto functions and the system also closes all the vents. On hot setting, still no fan in the middle, but at max speed the auto functions and air direction continue to work. If I switch either LH or RH dial to cool, the system defaults back to all flaps closed and hot air.

Ive cleaned and tested the control panel, evaporator and heater core temp sensors; all appear to be working correctly. I suspect the sword may be to blame for the two speed fan, but haven't found a good guide on how to diagnose it properly. Also, potentially related, I have a large voltage drain on either the auxiliary coolant pump or heater control valves.

Any thoughts on where to go with diagnosing?
 

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What he said.
If you own a ohmmeter, you can test the resistor values. What year is your car?

Pins 1-2 resistance when cold is 1.0 Ohm
Pins 2-3 resistance when cold is 2.2 Ohms
Pins 1-4 resistance when cold is 0.7 Ohms

There's also a thermal protection built in, that opens in overheat conditions, to prevent resistor failure.
 

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I think the IHKA doesn't use the resistor, but the "sword" fan speed controller as you state in your original post. I have no idea how you'd bench test it, but there is guides online for replacing the transistors. doesn't seem too hard if you have the tools.

My own experience...the heater control valve circuit is actually really, really stupid on the IHKA. powered through a tiny, tiny microswitch in the cockpit control panel - no relays. When you have your driver temp wheel anywhere other than full hot, this switch is closed and the valves are controlled by the IHKA brain. When you switch to full hot, this switch is opened and the valves are de-powered and on full-open.

This doesn't sound so stupid, until you realise that switch is ridiculously undersized to have to deal with the current required by the heater valves. It quickly gets hot and builds a resistance eventually dying completely, or worse, damaging your control panel. If you remove your control panel there are 3 connectors on the back. blue 26-pin, little white 3 pin and a large black 2 or 3 pin connector (2 on earlier cars, 3 after about 1990). that large black connector is for the heater valves. On my car I have actually bridged the connector to bypass the control-panel micro. This robs me of "Full hot, always open" but I live in Australia... I will never, ever need full hot.

Worth looking at that circuit. Arm yourself with a wiring diagram!


good luck!
 

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some good links;
 

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Discussion Starter #6
Pete, you are correct, my car uses the sword style resistor. Its a 93 by the way, I should probably have that in my signature
Thanks for the info.
I have a wiring diagram, but I dont have a good grasp of the internal logic of the IHKA control. The full hot setting works as it should, but the A/C side seems to be either full cold or nothing I'm still not sure why it decides to shut the auto functions on/off based on temp; maybe I need to just start with repairing the sword and work my way through the system from there.

Ill poke around a bit and report back when I inevitably have more questions
 

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My car is a 93. Has a sword, and a resistor. I wasn't aware there was a version that didn't have a resistor. I hope you solve it.
 

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Discussion Starter #9
Hmmm, I always thought it was one or the other. I'll have a poke around under there a again. Where is the resistor located on your car?
 

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Discussion Starter #12
Update: problem solved; I had two bent pins on the IHKA
Must have mushed those over when I changed out the microfilter; explains why it was acting so crazy, both were "shorted out" into the same hole.
Got in there with a small pair of needle nose and straightened them out, all good now!
939439
 
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