We operated some BAe 146s in Mexico prior to us recieving them they had been stored in the desert.
During the first few months after delivery we had various electrical avionic glitches. Dust and lint was found in various PCBs and relay supports once this had been cleaned off we had few problems.
In my opinion the dust and crap helps to retain the condensation once a cold soaked air conditioned aircraft lands and the doors are opened.
I suggest that a good vac and brush out of these areas follwed by thorough cleaning of affected components with brushes and contact cleaner will do the trick.
Obviously its not a good idea to break down systems to do this. We thoroughly cleaned system after they were reported by the crews. By attritition all of the systems became good over time.
Another thing we found out is that pitot /static covers hold moisture in the lines, we had a pretty high turnover of servo/alts. I dont think that any manufacturer would suggest you leave these off. The operator I am with at the moment always leaves pitot static covers off and we have few problems.