Keep the pressure relatively low and use a wide fan jet.
Soak the wall, spray on brick acid to affected area (dilute 3 parts water with 1 part acid, adding acid to water, not the other way around), dwell for a couple of minutes and rinse away, low pressure.
Using low pressure should negate the need to clean the entire wall.
You will most likely have to repeat a few times. You may also have to increase the acid content.
Masking windows and doors is an option, especially if steel handles / hinges.
We have recently been carrying out a major job where acid isn't permitted. There are alternatives out there, the best is Safety Klean from Tensid, this is less likely to cause unwanted damage but does come at a cost.