I’ve been reading everyone’s posts about their car overheating and try to put in my 2 cents here and there… and I hoped it wouldn’t hit me as well.
Too late.

To break it down quickly: my car (’03 civic EX coupe) over heats and the gauge will go up to 3 quarters on the temp gauge(sometimes beyond). I thought it would be a faulty thermostat so I switched that out, bled all my coolant and replaced with new coolant. No air pockets/bubbles. Let the car run to check if my fans were working, and they were. Drove to work and back yesterday, and get home to see my temp gauge doing the same thing. I leave my motor running and popped the hood to find that my fan wasn’t running, even though I had checked it after replacing the thermostat. The car cools down when I press the a/c button, because doing this automatically turns on the second fan. But the radiator fan that should be turning on when the motor reaches an appropriate temp isn’t engaging. I am thinking that the radiator cooling fan temperature sensor/switch might need to be replaced. Any other ideas? Let me know what you think I should do..

 

Double check your fuses in the engine bay panel, the 20A fuse for it could be blown.
my ac cooling fan had the fuse pop and wouldnt turn on when i had my ac turned on, i couldnt figure out why my ac wasnt as cold as it once was, replaced the fuse, the fan works and the ac is icy

 

Didnt even think of looking at them. I just went out and checked the fuses.. They are all just fine. still stumped. Are there any signs that can point directly to the radiator cooling fan temp. sensor/switch?

 

Hmm.. have you checked / tested the Radiator Fan Relay?
In your under-hood fuse box, there are three relays lined up from top to bottom. The RFR is the one on top. (closest to windshield)

Have you tested the Radiator Fan Switch? To test it..

1. Remove it from the thermostat housing.
2. Suspend it in a pot of water so that only the bottom is in the water, and the terminals are facing up. *see pic
3. Heat the water. Keep and eye on the temperature of the water with a thermometer. Don't let the thermometer touch the bottom of the pot.
4. Measure the continuity between terminal 1 and 2.


*I scribbled these together to make it easier..

How the switch should appear when you're testing it. Terminals 1 and 2 shown.






If it doesn't work like it's supposed to, replace it.