I certainly can't speak for anyone else but myself here and or their coaches and engine compartments. Many guys have claimed they've done a bang-up job of cleaning their radiators and CACs even after they've been clogged for quite some time. And they did it without removing them. I don't know what kind of job can be accurately done. I don't doubt anyone who's done it.
All I know is, my engine compartment, the sides, the undercarriage etc. is so entangled, constricted, sealed, etc. that there's really no possible way for me to have done a thorough, accurate, complete, job of cleaning either the CAC or the radiator. Now, I had to remove my radiator anyways because it had a leak in it. A leak that there was no way possible for it to be fixed while in the coach.
So, out it came. And I pulled the CAC too, along with many other parts etc. But, my point here is, my radiator and CAC were both hideously clogged for about 35% of the total area. The only possible way for me to have accurately, completely and thoroughly cleaned it, was to do it, where I could get very close access to the fins etc.
As stated, I used ZEP citrus based industrial cleaner and a 2650 psi pressure washer. Absolutely "0" damage to the fins, at all. It still took several applications of the ZEP and even the wand of the pressure washer.
Now, that was my scenario. Does it mean that everyone's is that caked on there and in the fins like mine, not necessarily so. It could be that mine had been there since the dawn of time and, was just extra hard to break free. If you can get it 100% clean without removing them, than that's outstanding.
Scott
Scott and Karla SDFD RETIRED2004 Itasca Horizon, 36GD Slate Blue 330 CAT
2011 GMC Sierra 1500 Ext Cab 4x4 Toad
2008 Caliente Red LVL II GL 1800 Goldwing KI60ND