Aluminum heads...

I meant A/C condenser.These fins are very close together and you may not be able to see dirt even if you get eyes on it. The best way to get that dirt out is to remove the coolant rad, and flush the fins forward from the engine side. I use shop water at 50/55psi through a garden hose with an adjustable nozzle. I watch the discharge water. When the mud stops I quit,lol. Then I turn my attention to the coolant rad. If you have a thermostatic clutch fan, this is a good time to check it.