Old thread I know, but I am a big proponent of keeping refrigeration coils clean to help keep pressures in spec and air cold (and not musty-smelling). Any canned foaming coil cleaner meant for evaporator coils will be plenty gentle enough. The condenser coil is hard to hit (between the radiator and the trans cooler) so if you ever have to pull the radiator, THAT'S the time to clean/flush the coil (from the backside). And if you have trouble getting to the evap coil, a pump sprayer with a 90-degree nozzle will work through the air filter door (if you have one).