e32 IHKA fault

I've got a problem with a IHKA control unit from a 6/89 735i. Only 3 things on the whole hvac unit are working

1. The fan works when set to full on
2. The little yellow light on the front screen demister lights up when the button is pressed.
3. The interior temp sensor fan runs normally.

Every other function on the hvac has stopped working. I've read about the dry solder joints on the resistors in the ihka control unit and was wondering if these symptoms could occur because of that?

I've done some digging with the multimeter and found that everything than runs on the 12v part of the system is getting power but all 5v parts are dead.

Thanks guys!

A little late, but the problem is your heater sword, which controls the speed of the fan. http://www.bimmerboard.com/forums/posts/355700/

Hi Shogun. Thanks always for your help. It was the hvac computer. I had a spare sword and trying it didn't make any difference. The computer fixed everything up.