You will risk rinsing away lubrication on critical components as well as possibly allowing water and condensation to set. This setting moisture will promote rust and contamination. Direct water spray is a common mistake made by some consumers. Water used on equipment which is still hot from use can cause a variety of problems. The rapid cooling that occurs causes a drastic temperature difference to exist internally and externally, therefore allowing condensation to occur.
Metals also expand and contract due to temperature change.
Expanding and contracting components means that seams and seals are possibly opened. This would allow for internal components to also be exposed directly to sprayed water, and therefore run the risk of internal rusting resulting in accelerated wear and premature failure. Not only is a unit vulnerable when it is hot, but even a cool unit can be improperly cleaned. Many units have non-serviceable or maintenance free components. These are parts lubricated and sealed at the factory and unable to be serviced.