I have tested the relays, the fuses, and the fans itself, all of them work.

I used a safety pin to complete the circuit in the cable that attaches to the thermostat fan switch (the switch that is part of the thermostat housing) which DID turn my radiator and A/C fan on, so I know the fan's work from that. I figured the switch was bad, so I replaced the switch with no success. I then replaced the thermostat, it's still overheating and the fans are still not turning on.

The top hose gets very hot where I cannot touch it, however the bottom hose stays warm and I can keep my hand on it without being burned.

I am very confused on what could be keeping the fans from turning on. The car overheats and the temperature gauge goes to the hottest, so the fans SHOULD be turning on.. If anyone has any other tests I can run or have any ideas I'd be happy to hear them.

Edit: Here is a video explaining the safety pin method I used to test, only need to watch for about 40 seconds:

 

The fan switch is in the bottom of the radiator, as you know... If the bottom of the radiator isn't getting hot, your fans would not turn on. If the bottom of your radiator isn't getting hot, I would burp the cooling system thoroughly, and if that doesn't fix it I'd suggest a water pump.

 

Isn't the switch in the thermostat housing? That's where I see it on mine (honda civic 2002 EX 4 door) it also shows it there in the video...or is that not the switch?

 

Oh, my mistake, I was thinking about my Si. Yes, it's in the thermostat housing, but my comment still stands- poor circulation due to air bubbles or bad water pump could still be causing this, since the thermostat is basically the intake from the bottom of the radiator. A good way to test this would be to idle until your operating temp is reached, then manual turn the fans on. If you don't see the temp fall quickly, you have a circulation issue.

 

Operating temp would be near the half way mark right? Okay so here is one more question that I am really curious about....

My A/C Light comes on in the interior when I press it to turn it on...but the condenser fan does NOT turn on. Could this be related to the radiator fan not turning on when it gets hot enough as well? Here is a diagram of the circuit to help you understand:

https://www.manualslib.com/manual/12...age=203#manual



Let me know if I can provide you with anymore details or resources!

 

if you're able to jump it then you either have the wrong fan switch or the connector is bad

 

Correct, operating temp is a tick or two below 1/2. AC is a complicated beast, there are a lot of variables, but the two fans are not connected as far as I know.

 

Both cooling fans should be running at the same time when the A/C is on or if the coolant temperature at the radiator fan switch is above 199 degrees F.

 

Yeah so I guess I should try and find out why the fans don't come on when the A/C is on either.

 

Sounds like a fuse or relay issue. Does the AC actually work? If it gets cold only when driving forward at 30+ mph, then I'd definitely chock it up to an electrical problem. AC fans will not ALWAYS be on, they switch when the thermostat in the condenser tells them to.