I would definitely give it a good power washing. If you don't want to pay a professional to do it (I would consider doing so however, as they should know how much power to use without damaging or breaking up your brick), you should be able to rent a power washer and get some instruction on how to go about using it. We have our own power washer and use it a couple times a year on our patio and once on the house stucco. A first-time cleaning on an older house might take a more professional approach.

Please do not use a power washer on old brick. It is porous and not made like todays brick and it may crumble. I would use soap and water and a scrub brush. I do recomend you call in the professiomals to clean it though. You won't save much money if you distroy the brick. It shouldn't cost much just for cleaning and then you can paint it yourself

Try posting this on the Old House forum. I have cleaned wood siding using a $15 hand pump sprayer to apply the cleaner and a scrub brush on a pole.

Here is a link that might be useful: The Old House forum

thanks for the reply. for obvious reason i think i'm gonna call professionals i don't want mess up the house thanks to all