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Okay I'll start this off by saying that I am a new member and I couldn't find any info regarding this issue on youtube or google as far as I can find.So I figured I would check here in the hopes that someone could help me possibly.

I'll get straight to the issue I'm having with my 2005 Honda Civic Si 1.7l coupe. Awhile back my car was overheating and I had my radiator, water pump, thermostat replaced along with new radiator fan switch as well as a new coolant temp sensor. I also had to get a new headgasket.

The issue I'm having now with my car is that the fans both the radiator fan and ac fan both kick on as soon I turn my key to on but don't start the car. I've checked the relays and they don't seem to be the issue and I can't think of anything else that could be causing it.Engine is cold and not running either.

I'll include an attachment so you guys can see for yourself what I'm dealing with. Thanks for any help!!

 
Rep Power: 224

Is the A/C or defrost turned on?

 
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Nope.

 
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The fans can be turned on two ways; the PCM/ECU or the radiator fan switch. The PCM/ECU will only turn them on at a certain temperature. You can verify the coolant temperature it's reading with a scanner that shows live data. The radiator fan switch is located next to the thermostat. When the coolant temperature reaches ~199°F, the switch closes and turns on the fans. I would guess this circuit or switch is bad.

For starters, unplug this switch, do the fans shut off?

 
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Yes as soon as i unplug that switch both fans stop.

 
Rep Power: 224

Check continuity across the two pins with a meter. Should be open unless the coolant temperature is ~199°F.

 
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I just put the old rad fan switch in and that seems to fix the issue.

 
Rep Power: 222

Was the one you replaced aftermarket?

 
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I had ordered it on rockauto. Maybe I should've got an oem replacement.

 
Rep Power: 224

You should see if it came with a warranty.

 
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I don't think it did unfortunately.

 
Rep Power: 224

What brand/part number did you purchase?

On Rockauto, under "Electircal-Switch & Relay" then "Radiator Fan Switch" every single one has at least a 90 day warranty. Most are a year or more.