cedar shingles and what to do

The time has come to paint my house, I have cedar shingles. The nonweather sides
have turned black(it has been around15-20yrs since there last upkeep) This black (mold?) is heavy and runs from the bottom up
How do I clean this off? it seems to run deep into the shingle.
I have tried a TSP wash, That really didnt work, then I tried a bleach mixture, that didnt work at all
Should I try a pressure washer?
On the weather sides there is hardly no black, (mold?) Im pretty sure I can scrape those sides.
Anyone have any ideas? after I get the place "clean" what should I use for, paint? stain? primer coat?
Thanks again, Dave

Het jotul
I tried the tsp and bleach neither worked. So I went for the pressure washer,
let me tell you that worked. It kind of made a rough surface, and I will have to replace maybe one
square over the whole house, which is ok, the washer brought me back to raw cedar.
I got 3 months of good sun to finish the job
What are you looking at, years of finish, like mine?
Dave