My old radiator started leaking. I had to pour water in that thing every 3 days to keep it topped. However, temps never go pass the 1/2 way mark (it sits around 3/8's mark actually).

Just yesterday I replaced it with an aluminum radiator with stock fans. After refilling the coolant and bleeding with the radiator cap off, I noticed the fans never turn on. The car doesn't overheat or anything even with the car idling there for over 20 minutes. It stays at the 3/8's mark. The top of the radiator gets SUPER hot though (like I can't even touch it).

The fan relay in the fuse box looks fine. I even swapped it with the heater motor relay and still no fans. The fans DO turn on if I turn on the AC though so I'm guessing the fans work ok.

I did some searching, and what is this fan switch ppl keep saying to check? What else can I check? Even though it doesn't overheat, the radiator and the motor seem to get reeeeeeeeally hot where I can't even touch them.

 

The temperature switch is probably faulty. It engages the fan after a certain temperature to prevent overheating. The fan will always go on with AC as logn as they are intact.