In detail with pics
Is your E36 climate control display dark? Do buttons lighten up and darken randomly, with button illumination apparently unrelated to what the heater and A/C are actually doing at the moment? Does it turn off and reset itself randomly?
Capacitor. The original capacitor is 0.47 uF. However, because It is being used as a filter, people who seem to know a lot more than me say that the size does not really matter, and it doesn't even matter if you put a polar capacitor in backwards. I used a 1.0 uF capacitor in both my E36s because that was what the local Radio Shack had on hand. The first one was ceramic. The second one was tantalum. Both were polar. From what I read, tantalum capacitors are better. The first repair is still working fine 5 years later.