2004 Honda Civic Show Asked by in Corona, CA on April 17, 2009 My cooling fans do not turn on when idling. I bought the cooling fan switch, I just need to know where it is located on my car. Thank you. 1 reply Report The radiator fan control switch is located on the transmission side of the engine near the EGR valve in same location
as the coolant temp sensor for the Fuel Injection ECU. Yeesh, still updating this thread. The car ended up misfiring pretty badly recently, and after limping it home (this car has never left me stranded, even when battered and bruised) I found a pretty fouled up (kind of green) #3 spark plug (12k miles on these, give or take.) I finally got my hands on some block tester fluid, and surprise surprise, it turned a little green. At least a noticeable green compared to the dark blue it's supposed to be. So, I yanked the head off and replaced the head gasket/bolts/t-belt/tensioner/water pump. The old head gasket looked fine and the head was awfully flat, but the one head bolt seemed to require less effort to crack loose. I don't know if that matters or not. I did notice a very very slight scratch-mark on the one cylinder wall (#2) that looked like a crack, but I couldn't feel it and couldn't see it from the water jacket side, so I'm chalking it up to a scratch. I wasn't interested in yanking the block, anyway. Flush some things out, reassemble, fire it up, and it's idling at 1500RPM and is heating up (~220*). Let it sit overnight, disconnect the battery for 10 min, lift the nose of the car in the air to bleed it, and fire it back up. This time it actually starts to idle down, sounds smooth as usual, revs fine, fans are kicking on and the temp is normal, etc. I assume it's bled, but I'm skeptical. I honestly don't know if the headgasket was the problem, but I'm not interested in rebuilding/replacing the motor, so this is basically the last of the work. If it stops overheating I'll continue to drive it, but if in a few weeks it overheats again I'll probably unload it. A fast question about the timing belt - when replacing it, I did it Honda's way where I had it set to TDC, rotated the crank pulley ~3 teeth, and while holding the wrench on the crank pulley I tightened down the tensioner pulley. I did this probably 10 times, because it just didn't seem tight enough to me (based on other cars I've worked on), but after a while I figured this is what's required and just buttoned it back up. When I got the car running, it seems like there is a slight whine. Honestly, I haven't driven the car in a week and don't really recall if it used to "whine" or not, so maybe it's a normal noise and I'm overthinking this, but can you even over-tighten the belt when doing it Honda's way? I wasn't prying the tension pulley up or anything, so I honestly don't understand how I could've over-tightened anything. Thoughts? Edit: To answer axis11, I don't think the car was burning anything. When it would overheat, I usually ended up adding a tiny amount of coolant, but I just assumed it was being pushed out of the overflow/around the radiator cap, based on the residue left over. Cooling fan switch sensor? Registered!! Thread Starter
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Cooling fan switch sensor? 2004 Civic LX - I'm having some overheating issues and need to know what part/s to order. I had it worked on a few weeks ago on the side and have a list of parts replaced - head gasket (sent to machine shop), radiator, thermostat, numerous sensors (he didnt list which ones), sensor in the thermostat housing. He said I need a sensor for the cooling fan switch because the fans arent turning on like they should. Also said I need a new "hose". He is now nowhere to be found, wont answer calls or texts, so now I need to find someone else to do the work. I need to know WHAT to order before I have it worked on. I dont loose coolant unless it gets hot. No heat rising and it holds coolant great. Before it was a head gasket and a leaking radiator. Those are now fixed but still having some minor overheating issues. Temp gage will raise, turn on defrost fans and it will drop. Sometimes, if its really hot outside it will get almost to the red before it drops dramatically. When it drops fast I can feel the cooling fan kick on. About 2 months ago I had a shop put new cooling fans, a relay and new radiator cap on it. Any suggestions?
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Re: Cooling fan switch sensor? it still sounds like your head gasket is the problem to me Registered!!
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Re: Cooling fan switch sensor? the switch is right near the thermostat. maybe you need a honda part instead of a no-brand part. keep bleeding the air out of the coolant system
the heater core could have a leak too! bypass it for a while to see it thats the problem. overheating is very bad, so turn it off when its too hot! if it already got too hot, you may need a new head gasket already. Registered!!
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Re: Cooling fan switch sensor? Quote: Originally Posted by Sarahwv2910 Those are now fixed but still having some minor overheating issues. Temp gage will raise, turn on defrost fans and it will drop. Sometimes, if its really hot outside it will get almost to the red before it drops dramatically. When it drops fast I can feel the cooling fan kick on. Does the temp gauge move when it idles or have you driven it? I'd try driving it up on a ramp and burp the radiator to make sure you don't have an air bubble in the coolant. I can't feel the fans kick on in my car so I'd sit there and let it idle and watch them to see if if they turn on or not. If it starts getting toward the top of the temp sensor pull over and pop the hood and see if they are on. Registered!! Thread Starter
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Re: Cooling fan switch sensor? Ive had it back a week. The temp gage has gone to the red once but I was able to pull over, turn on the defrost fans and get it cooled. It will climb but doesnt go above 3/4. He bled the system but only once. I can bleed it again. Fans are NOT coming on, so I know its got something to do with that. I can order a honda switch and have it put on. Registered!!
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Re: Cooling fan switch sensor? Stop and go traffic for the last hour and it started getting hot. Pulled over, popped the hood and the cooling fans are not on. Ive now got the engine off and the radiator fans blowing waiting for the temp gage to drop so I can fill up the coolant cause I know its low again. It burns up when the gage climbs. Ive checked and checked for a leak and cant find anything unless its gotten too hot and boiled the coolant. Then I can see dripping underneath. Registered!!
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Re: Cooling fan switch sensor? Quote: Originally Posted by Sarahwv2910 Stop and go traffic for the last hour and it started getting hot. Pulled over, popped the hood and the cooling fans are not on. Ive now got the engine off and the radiator fans blowing waiting for the temp gage to drop so I can fill up the coolant cause I know its low again. It burns up when the gage climbs. Ive checked and checked for a leak and cant find anything unless its gotten too hot and boiled the coolant. Then I can see dripping underneath. how is the coolant level in the overflow bottle?....is it at the top? high? completely full? if so thats your head gasket Registered!! Thread Starter
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Re: Cooling fan switch sensor? Reservoir tank was very low, almost empty. I filled that up first and then filled the radiator Registered!!
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Re: Cooling fan switch sensor? Quote: Originally Posted by Sarahwv2910 Reservoir tank was very low, almost empty. I filled that up first and then filled the radiator after all that coolant gone, it sounds like a bad head gasket or bad head! does it blow out steam when its hot? any sign of water anywhere? when you turn the AC on, doesnt it turn on your fans? if you post your city, maybe someone here has a mechanic to help you. Last edited by alex_nyc; 06-15-2015 at 05:56 PM. Registered!! Thread Starter
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Re: Cooling fan switch sensor? No, the only fans running are the radiator fans. No steam, no white smoke, nothing. Just heat and loss of coolant once it gets hot. I fought with it all evening trying to keep it cool. Im in Charleston, WV. On a good note, the guy that worked on it last just called me and is going to put the parts on it tomorrow. Im praying this fixes this issue and it becomes the reliable car again that its always been... If you think a good mechanic is expensive, try hiring a bad one
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Re: Cooling fan switch sensor? Quote: head gasket (sent to machine shop), Also said I need a new "hose". He is now nowhere to be found, wont answer calls or texts, Why does this sound like some clown off of craigslist? Quote: sensor in the thermostat housing. He said I need a sensor for the cooling fan switch because the fans arent turning on like they should. Um, the sensor whose wires stick out toward the front? That sensor in the thermostat housing WAS the fan switch. Quote: Those are now fixed but still having some minor overheating issues. Temp gage will raise, turn on defrost fans and it will drop. Sometimes, if its really hot outside it will get almost to the red before it drops dramatically. Overheating is never minor! It only takes one good one to trash the head gasket that was just replaced and warp the head. Quote: I need to know WHAT to order before I have it worked on. Someone has to figure out what is actually wrong first. Maybe start with figuring out if the wiring at the fan switch on the thermostat housing will turn the fans on. Registered!! Thread Starter
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Re: Cooling fan switch sensor? He may have said that... im not a mechanic so am not sure what all he replaced. He works for a shop here but is doing the work on the side so we both save money. We're going to work on it tomorrow and hope it doesnt overheat again Registered!!
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Re: Cooling fan switch sensor? Quote: Originally Posted by Sarahwv2910 He may have said that... im not a mechanic so am not sure what all he replaced. He works for a shop here but is doing the work on the side so we both save money. We're going to work on it tomorrow and hope it doesnt overheat again if it has already overheated then chances are the head gasket is toast Registered!! Thread Starter
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Re: Cooling fan switch sensor? The temp gage got about 2 or 3 notches below the red and I was able to pull over and let it cool down. It hasnt hit the red yet. Registered!!
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Re: Cooling fan switch sensor? Quote: Originally Posted by Sarahwv2910 The temp gage got about 2 or 3 notches below the red and I was able to pull over and let it cool down. It hasnt hit the red yet. theres no way to tell the exact temp or if there was damage if you continue to loose coolant, IMO its either Head gasket/warped head or heater core leak. Registered!! Thread Starter
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Re: Cooling fan switch sensor? Im only loosing coolant when it gets hot tho. It didn't get hot driving to work or to lunch and back and the levels are normal Registered!! Thread Starter
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Re: Cooling fan switch sensor? Next step is going to be flush the heater core and see what it does. Another head gasket fix will have to wait til we've exhausted all other options. The mechanic wouldn't work on it last night because it started to sprinkle.... guess he thought he'd float away. So im taking it to the shop my friend uses and dropping it off for the day to see if they can diagnose it and work on the heater core Registered!!
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Re: Cooling fan switch sensor? Quote: Originally Posted by Sarahwv2910 Next step is going to be flush the heater core and see what it does. Another head gasket fix will have to wait til we've exhausted all other options. The mechanic wouldn't work on it last night because it started to sprinkle.... guess he thought he'd float away. So im taking it to the shop my friend uses and dropping it off for the day to see if they can diagnose it and work on the heater core
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Re: Cooling fan switch sensor? Quote: Originally Posted by Sarahwv2910 Next step is going to be flush the heater core and see what it does. Another head gasket fix will have to wait til we've exhausted all other options. The mechanic wouldn't work on it last night because it started to sprinkle.... guess he thought he'd float away. So im taking it to the shop my friend uses and dropping it off for the day to see if they can diagnose it and work on the heater core I had to stop working on my civic several times yesterday due to the rain too! To save time you might want to bypass the heater core and see if that's the fix. Registered!!
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Re: Cooling fan switch sensor? Quote: Originally Posted by Sarahwv2910 Next step is going to be flush the heater core and see what it does. Another head gasket fix will have to wait til we've exhausted all other options. The mechanic wouldn't work on it last night because it started to sprinkle.... guess he thought he'd float away. So im taking it to the shop my friend uses and dropping it off for the day to see if they can diagnose it and work on the heater core I doubt there is a problem with the heater core. Heater cores leaking in Civics is rare and a leaking core is usually pretty obvious. A small leak will usually show up as fogging on the windshield at the defroster vents and a bigger leak will dump coolant out of the floor heater vents. Antifreeze also has a sweet smell that would think you would notice if the leak was anywhere in the heater. If you think a good mechanic is expensive, try hiring a bad one
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Re: Cooling fan switch sensor? Quote: Originally Posted by Sarahwv2910 He works for a shop here but is doing the work on the side so we both save money. Accurate diagnosis and quality repairs save money. Quote: Originally Posted by Sarahwv2910 Next step is going to be flush the heater core and see what it does. This thread sounds like the equivalent of rewiring an entire house then discovering the lamp was just unplugged. Registered!!
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Re: Cooling fan switch sensor? Quote: Originally Posted by ezone This thread sounds like the equivalent of rewiring an entire house then discovering the lamp was just unplugged. Thread Thread Starter Honda Civic Forum Last Post 7thgensurvivor Mechanical Problems/Vehicle Issues and Fix-it Forum 38 08-29-2015 11:50 AM danace99 Mechanical Problems/Vehicle Issues and Fix-it Forum 23 06-28-2015 08:49 AM Bruce.Ringler Mechanical Problems/Vehicle Issues and Fix-it Forum 12 06-18-2015 08:12 AM hokiedad4 7th Generation Civic 2001 - 2005 1 05-03-2015 10:06 PM bsmiley 7th Generation Civic 2001 - 2005 3 04-27-2015 01:27 PM What sensor turns on the radiator fan?On most modern cars, the cooling fan is controlled by the Engine Control Unit (ECU) which gets a signal from the coolant temperature sensor.
Where is radiator fan relay switch?The fan relay is usually located near the bottom of the engine compartment on a metal frame member. The metal acts as a heat sink to keep the fan relay cool. So, unplug the connector at the relay and repeat the check for power. If you get power, you've got a bum relay.
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2004 honda civic radiator fan switch location
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