aircon control unit

What year and model?

Sounds like BS to me. I swapped a AC control unit on a 735i with one from my old car (long story) and it was a doddle even for a relatively unskilled DIY'er like me.

Check the final stage resistor unit. It is a bit expensive but very easy to replace on many models.

Dunno. Certain types have a memory which distinguishes which key is used at the time - a sort of him and hers thing. It's possible the software has to be loaded in.

Wouldn't make the control panel go dead, though.

This is a very common problem on late model E36s. It's not that hard to fix the circuit board, there's a web page that shows you how. Sadly I didn't bookmark it.

all sorted now, although not a car techi i removed the unit and replaced with a new one, the unit cost £228, phew.... got £38 px for the old one so they'll replace a circuit board in that and put it back on the shelf, what a ripoff. The biggest laugh of all was when i went onto the BMW dealers parts department, the total lack of help and indifference was astounding, together with the sharp intakes of breath that i had the audacity to do summat myself and constant reminders that it "needs coding in" and the "right equipment" to carry out such a high tech operation, took me all of