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My son has a 03 Civic. It has 2 radiator fans. I noticed the other day when he had his hood popped up that just 1 fan was running. I unplugged the wires from the running fan and plugged them into the fan that wasn't running. To verify that the non running fan motor wasn't bad. It turned on when plugged in. So my question is....Are they both suppose to be running? Does one run and the other kick on and off as needed? Do they have different temp sensors? I havent found a direct answer to that yet in the forums. How Honda has it set up. Thanks

 
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its normal, the fan that was not running only runs when you have the A/C on

 
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Ok. Thank you.

 
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03 should have both fans running at the same time every time they run, no matter which system turned them on.

Look in a wiring diagram.

 
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Just had this problem, easy solution is check the fuses/relays. The two fans have separate fuses and relays in the underhood fuse box (I believe they are both 20amp fuses). If one works and the other doesn't, but does when wiring is switched, it is almost assuredly that.