The front is the exhaust I assume? The back fins where the intake air first comes in is where dirt accumulation will affect moisture removal. The cold coils that the moisture in the air condensates on…
A brush would work good, but if it’s running and the coils are properly chilled and wet, it’ll kinda be a sticky mess. I’m gonna steal @Cap_Ron dehum pic again (not pickin’ on ya grobro, it’s just such a great example )
)