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2005 Civic Ex SE
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Discussion Starter #1
I am not looking to be bashed. I didnt get frustrated and just ask this. I have been searching and calling numerous people since march 2012 and have not been able to figure this out. My fans work with ac on. I can also cool down coolant with heat on full blast with no recirculation. I have replaced the fuses and relays. The temp sensor and rad fan switch. Rad cap and flushed with cleaner and hose like 5 times. Cleaned rad and block many times. Tried multiple thermostats. Ran with no thermostat. Car only heats up at idle. Other than replacing rad now, i have no idea what else it could be. Fans just will not turn on by themselves. Please help. Im getting pissed off with the car and no one can seem to help with this. Thanks.
 

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Okay so does the car over heat? or only heat up at idle?

Cause you never really said what the main issue was other then the fan doesn't come on other then when you turn A/C on.

Are you a Android or iOS user? If you are I'd suggest getting a Bluetooth OBDII reader and install an app to read the PIDs.
 

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2005 Civic Ex SE
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Discussion Starter #3
sorry. i guess i was a little unclear. i have android and use the torque app to monitor my ecu. the car will over heat if i am not in the car to monitor it. i have let it get to 240f and the fans will not turn on. if i flush the system and put it back together it will run normally and the fans will work for a few mins like normal. but then it will stop again and my fans will not work. the last two things i can think of is the radiator is clogged and it is not flowing properly or the water pump is bad. but i highly doubt the water pump is the issue. the radiator is slightly bent being that only one screw fits to mount it. i do not have any leaks though. if i hit the gas at idle the temp goes up, not down. if it was a water pump issue the temp would go down when revving. i am so stumped and cannot find anyone here to help me. honda keeps telling me to bring it in and wont give me any advice.
 

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1966 Volvo
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Get yourself a multimeter ensure your rad fan switch is seeing the right input voltage to turn the fan on. Look at a cooling system electrical circuit diagram and start diagnosing there. Each part of the system will have an input and output signal (voltage) and you need to find out where your system is malfunctioning. Could be as simple as a bad ground, or a faulty circuit in your ECU. It's a lot of work, but will save you a fair amount of cash if you do it instead of a dealer tech.

Save this to your computer. It's pretty big so you can read everything.



And here's the troubleshooting for it. You want Test "B".

https://www.dropbox.com/s/eumioz2jq2fd6jp/Cooling.pdf
 

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2005 Civic Ex SE
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Discussion Starter #5
i dont think the fan switch is the issue. i have tried using 2 different ones and still have the same issue. im thinking that the radiator is a little clogged and the coolant isnt flowing properly so the fan switch isnt fully submerged in coolant. because when i do a flush it will work fine but not for very long. plus when i turn on the ac both fans turn on.
 

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\/Your Mom Was Here\/
Vibe GT
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4,833 Posts
i dont think the fan switch is the issue. i have tried using 2 different ones and still have the same issue. im thinking that the radiator is a little clogged and the coolant isnt flowing properly so the fan switch isnt fully submerged in coolant. because when i do a flush it will work fine but not for very long. plus when i turn on the ac both fans turn on.
Are you losing coolant?

Dumb question but have you properly bled the system each time as well?
 

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2005 Civic Ex SE
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Discussion Starter #7
Coolant is not leaking and i have done a test with the block tester fluid and it passed. I also fill it up while running and let the air bubbles stop completely before i put the cap back on. Im frustrated because it has been doing this for a while now.
 

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2005 Civic Ex SE
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Discussion Starter #8
Well i just replaced the radiator today and the fans still dont work on their own. Im at a loss. The old radiator was more bent than i thought. It looked like it had been kicked in. But this one is new and still doesnt work. Idk what else to do.
 

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Have you checked your grounds and made sure you are getting enough power to the fan motor to move it?
 

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Is your coolant reservoir filling up with coolant?

Do you know whether or not your water pump is working?

Also, check the wiring for continuity all the way from the fan itself back to the fuse box.


EDIT: These engines are a real f-ing pain to bleed. It's not as simple as filling it up, and waiting for the bubbles to stop. You'll have to run it for a bit, top it off, cap it, run it, top it off, rinse and repeat.
 

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2005 Civic Ex SE
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Discussion Starter #12
Fans turn on and cool car just fine but only with ac running. The fans just wont run unless i have ac on.
 

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Fans turn on and cool car just fine but only with ac running. The fans just wont run unless i have ac on.
Does the reservoir fill up with coolant?

Are you 100% sure that the cooling system was fully bled?
 

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oz33916; said:
i do not have any leaks though. if i hit the gas at idle the temp goes up, not down. if it was a water pump issue the temp would go down when revving. i am so stumped and cannot find anyone here to help me. honda keeps telling me to bring it in and wont give me any advice.
Classic symptoms of a head gasket blown. And if you got it to 240*, then most likely the head is warped.


Coolant is not leaking and i have done a test with the block tester fluid and it passed. I also fill it up while running and let the air bubbles stop completely before i put the cap back on. Im frustrated because it has been doing this for a while now.
Did you raise up the front of the car and turn the heat on full blast? Did you squeeze hoses to work out any bubbles?
IDK what block tester fluid is

Well i just replaced the radiator today and the fans still dont work on their own. Im at a loss. The old radiator was more bent than i thought. It looked like it had been kicked in. But this one is new and still doesnt work. Idk what else to do.
Take a drill battery, unplug fan and figure out a way to connect the battery to your fan. If the fan works, then you know its either the wiring with a short and/or fuse is blown.



If you hit the gas at idle and the temp goes up immediately, then you have alot more issues then just the fan.


The Cooling fan and the AC condenser fan are controlled indiividually. If they both come on then thats where to start looking
 

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You overheated and are working on ruining another engine because you cant listen to advice we gave you in the last thread you had about this. Either dont drive the car, or make it so the fan runs, you have NO other options unless you want to keep ruining motors. At this point you are being so silly I cant even feel bad for you.

The fan requires +12v and ground. Most likely it is the +12v is keyed and the ground is switched. Get an $8 multimeter, look at the wiring diagram, find out which of the two is missing from the fan then go from there. This is NOT complex.
 

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From the wiring diagram above it looks like you can jumper the two terminals on the coolant temp switch connector (harness side, obviously) while the car is on and it should turn the fans on. If it doesn't the problem is somewhere else. If it does, the problem is that either the temp switch is bad, or the temp switch isn't actually getting hot enough to trigger.
 

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From the wiring diagram above it looks like you can jumper the two terminals on the coolant temp switch connector (harness side, obviously) while the car is on and it should turn the fans on. If it doesn't the problem is somewhere else. If it does, the problem is that either the temp switch is bad, or the temp switch isn't actually getting hot enough to trigger.
Yep, I told him that in the last thread, he doesnt want to jerry rig the fan on until he finds the problem, instead he would rather just keep blowing up engines.
 

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97 honda HX-07 STI
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i dont think the fan switch is the issue. i have tried using 2 different ones and still have the same issue. im thinking that the radiator is a little clogged and the coolant isnt flowing properly so the fan switch isnt fully submerged in coolant. because when i do a flush it will work fine but not for very long. plus when i turn on the ac both fans turn on.
Sounds like the radiator. But that is my 2 cents. Could be the radiator cap maybe. Have you done a pressure test on it?.
 

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2005 Civic Ex SE
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Discussion Starter #20
after replacing almost every part in the coolant system...it ended up being the very last thing that i hadnt replaced. im guessing the gasket on the waterpump was bad. replaced the waterpump when i swapped out head gaskets and timing belts and am no longer having overheating issues. thanks for all the help guys.
 
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