The correct test for a fan clutch is described in this thread
My personal way to test a radiator is:
1) with the engine cold, jam the fan so it can't spin, or remove it;
2) hose down the radiator & start the engine, allowing it to warm up slowly at idle;
3) when the thermostat opens, the water on the radiator fins will evaporate quickly, so observe HOW it dries;
4) if a line appears & remains distinct for a while, it means the tubes that stay wet are blocked, and little or no coolant is flowing thru that part of the radiator (usually the bottom, where sediments collect);
5) if more than ~20% of the radiator stays wet, replace it. If more than 10% stays wet, consider replacing it soon, or at least getting it backflushed & pressure-tested.