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Discussion Starter #1
Hi all,

So the fan on my Civic does not work. I checked everything and I've come to the conclusion that the relay is f***ed! So I am wondering, where exactly is the main fan relay located. I need to get this sorted ASAP..

Thanks, Pete
 

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Discussion Starter #3 (Edited)
Hi Scaramanga!

Sorry, I should have made my opening post clearer!

It's the main radiator fan I am referring too. I am looking for the location of the relay of the main radiator fan.

Thanks.
 

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Hi Scaramanga!

Sorry, I should have made my opening post clearer!

It's the main radiator fan I am referring too. I am looking for the location of the relay of the main radiator fan.

Thanks.
is the car over heating ?
the fan will only kick in after the water temp gets too hot and in this weather that will take a long time
 

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Unless you have a faulty coolant sensor (usually the one at the rad base) the fan won't come on unless you are stuck in traffic on a hot summer day.
 

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aas far as i can remember it the one circled in yellow



BUT...

the chances are that's not your problem
as others have already said the chances are it's not getting up to temp to switch the fans on or the radiator temp sensor is faulty


the coolant fans don't kick in unless the coolant temp reaches 80 degrees c or above, if you have an OBD adaptor and something like the torque app for android you can easily monitor the coolant temps and see if the fans kick in once the temp reaches 80 degrees c

unfortunately things get a little more complicated than just a fan relay as the air conditioning fan is tied into the equation
there are 3 relays that control the fan switching
the 2 you see in the picture ( black one controls AC fan and the grey controls coolant fan )
the third relay is buried inside the same fuse box and is not a changeable part without a bit of surgery

between the 3 relays they control which fan comes on and at what speed

if the car is not overheating the chances are it's not getting up to temp high enough to kick the fans in

everything i talk about here is to do with the 2.2 diesel it should be the same or very similar for the 1.4 petrol with AC
 

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Discussion Starter #7
is the car over heating ?
the fan will only kick in after the water temp gets too hot and in this weather that will take a long time
Unless you have a faulty coolant sensor (usually the one at the rad base) the fan won't come on unless you are stuck in traffic on a hot summer day.
Thanks,

I have checked this with an OBD 2 tool. The coolant goes up to 140oC and the fan doesn't engage.

I'm sure that it's not the sensor, as I've disconnected the sensor and when I turn the key (To the 1st position, on the ignition, when all the warning lights ignite on the dash) the temp gauge goes up to the top. I.E. over heating.

When I put the sensor back together and turn the key on the 1st position it doesn't move.

When I turn the key, I leave it running and the gauge goes up to the top. So it is over heating, basically because the fans aren't running, to cool the radiator..

Unrelated, but I've also swapped about the fuses and this didn't salve the issue. So the relay is the last thing to check.

I really appreciate this help. Thanks! :)
 

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Discussion Starter #8 (Edited)
aas far as i can remember it the one circled in yellow



BUT...

the chances are that's not your problem
as others have already said the chances are it's not getting up to temp to switch the fans on or the radiator temp sensor is faulty


the coolant fans don't kick in unless the coolant temp reaches 80 degrees c or above, if you have an OBD adaptor and something like the torque app for android you can easily monitor the coolant temps and see if the fans kick in once the temp reaches 80 degrees c

unfortunately things get a little more complicated than just a fan relay as the air conditioning fan is tied into the equation
there are 3 relays that control the fan switching
the 2 you see in the picture ( black one controls AC fan and the grey controls coolant fan )
the third relay is buried inside the same fuse box and is not a changeable part without a bit of surgery

between the 3 relays they control which fan comes on and at what speed

if the car is not overheating the chances are it's not getting up to temp high enough to kick the fans in

everything i talk about here is to do with the 2.2 diesel it should be the same or very similar for the 1.4 petrol with AC
Thanks so much!

So all the relays to do with the engine/Fan and A/C are under the bonnet in the box. I assumed it might have been somewhere under the steering wheel as when I flash the head lights. I hear a clicking sound coming form underneath the steering wheel.

I have explained this in my last post.

The coolant is reaching a temperature of 140oC. Yet the fans are not kicking in. When I let the car run, the heater gauge goes to the top. So it is over heating.

There will be similarities between the 2.2 and 1.4 indeed.

Anyway, thanks so much for the help. It's very much appreciated.. :)
 

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140 degrees C? You're 'avin a laff. The coolant boils in a car cooling system (at 15PISG) at somewhere about 125 - 130 deg C. Have you got loads of steam coming from your rad?
 

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Discussion Starter #10
I've checked it again since.

Apologies, I mean't 140F. Which is 60C (I know nothing about this kinda thing, so please bare with me! :)). After checking it there again. The temp going up to 100C and staying there, but it's moving slightly down to the high 90s... While all this is happening. The heater gauge is up to the top on the speedo!

Thanks for the reply!
 

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Discussion Starter #12
Have you confirmed that the fan is working? - via a direct/temporary power feed.
Yes, I have! Fan works perfectly.

I'm really thinking the relay is the problem to be honest! So if the relays for the fans are located under the bonnet, it should be grand. But I need to be 100% sure, before replacing them.

Thanks.
 

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you could pull out the relay and momentarily short the 2 large pins in the fuse box which would simulate the relay switching
if it is the relay that's faulty the fans should kick in

does your AC work ?

by rights when the AC is on and working both fans should spin
the 3 relays i mentioned earlier control which fans spin and at what speed, what they do is either divide the voltage to both fans ( 6 volts to each fan ) to spin them at half speed or provide 12 volts to each fan depending on weather the engine temp has reached 80 degrees c or above ( coolant fan ) or the AC pressure sensor has reached a particular pressure level which then switches the AC fan in at full speed and disengages the AC compressor

the 2 relays you can see in the fuse box are for the AC ( black one on the left ) and the radiator coolant fan ( grey one on the right )
the 3rd relay which is inside the fuse box which you cannot see is linked to the other 2 relays and switches between ground and 12 volts

the main fan fuse should be in the fuse box under the bonnet either fuse 18 or 19 i think but it might be worth checking em all
 

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Discussion Starter #14 (Edited)
you could pull out the relay and momentarily short the 2 large pins in the fuse box which would simulate the relay switching
if it is the relay that's faulty the fans should kick in
I have done this. I put wire from the 3rd pin on the bottom of the black fuse, then I attached it to metal on the engine bay to ground it. Now my fans are running 24/7..

I replaced the relay (Grey) circled one above. This didn't solve the issue. Fans still not kicking in!

does your AC work ?
Yes, A/C does work grand!

by rights when the AC is on and working both fans should spin
the 3 relays i mentioned earlier control which fans spin and at what speed, what they do is either divide the voltage to both fans ( 6 volts to each fan ) to spin them at half speed or provide 12 volts to each fan depending on weather the engine temp has reached 80 degrees c or above ( coolant fan ) or the AC pressure sensor has reached a particular pressure level which then switches the AC fan in at full speed and disengages the AC compressor

the 2 relays you can see in the fuse box are for the AC ( black one on the left ) and the radiator coolant fan ( grey one on the right )
the 3rd relay which is inside the fuse box which you cannot see is linked to the other 2 relays and switches between ground and 12 volts
I see. Do you think is it worth replacing the Black A/C relay?

However, it's looking like it's the 3rd relay that you are mentioning, that's under the fuse box. Which is causing the issue....


the main fan fuse should be in the fuse box under the bonnet either fuse 18 or 19 i think but it might be worth checking em all
It's fuse 18 indeed! I have replaced that also! Still no good unfortunately.


Thanks for the advice! :)
 

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you say the AC works just fine
does the AC fan kick in and out as it should while the AC is on ?

i'm not sure what you mean by " I put wire from the 3rd pin on the bottom of the black fuse, then I attached it to metal on the engine bay to ground it. "

which black fuse ?

if the third relay inside the fuse box packs in the fan should still spin but only at half speed


i think your next thing to look at are the engine temp coolant sensors, these are not thermostats so shorting them out won't do you any favours and are wired to the ECM
how you would test these is another matter

reading through the thread again..
when you temp reaches 90c your temp gauge should be around half way if it's going straight to the top that could be an indication of a faulty sensor
check with your obd tool again and see what temperature sends the temp gauge to the top
like i said 90c should really be about half way on the temp gauge ( ish ) but certainly not at the top of the reading


armchair diagnostics is nigh on impossible :(
 

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Discussion Starter #17 (Edited)
you say the AC works just fine
does the AC fan kick in and out as it should while the AC is on ?

i'm not sure what you mean by " I put wire from the 3rd pin on the bottom of the black fuse, then I attached it to metal on the engine bay to ground it. "

which black fuse ?

if the third relay inside the fuse box packs in the fan should still spin but only at half speed


i think your next thing to look at are the engine temp coolant sensors, these are not thermostats so shorting them out won't do you any favours and are wired to the ECM
how you would test these is another matter

reading through the thread again..
when you temp reaches 90c your temp gauge should be around half way if it's going straight to the top that could be an indication of a faulty sensor
check with your obd tool again and see what temperature sends the temp gauge to the top
like i said 90c should really be about half way on the temp gauge ( ish ) but certainly not at the top of the reading


armchair diagnostics is nigh on impossible :(

The A/C fan does work. I have cold or hot air in the cabin.

No, the main fan doesn't kick in or out. It doesn't work while the A/C is on or off..


Sorry, I meant the grey fuse, circled above! Okay, so basically I bypassed the grey relay with wire. One of the pins on the relay is ground I assume. When I place wire going from the relay to a bit of metal. This seems to ground the relay. Then the fan spins at a fast speed, when the wire, comes in contact with metal. The fans continue to spin until I break the connection.

I am wondering, if it would be a good idea to buy a new black A/C relay. (Sorry, meant relay and not fuse.)

Okay, so it's safe enough to assume that it's not the inside fuse so? That's a relief. :smile3:

Right so where are them coolant sensors? They aren't the connections which are leading into each fan by any chance?

From memory, the top of the gauge is 100 degrees Celsius. This goes down to the high 90's on the OBD tool. But I can check again tomorrow and report back!

It is very difficult for ye to diagnose this over the internet. However, I am extremely grateful with all the advice. I'd have no clue other wise. So it's good that I am getting things eliminated. So thanks. I'm just pissed off with the car! That's all. :smile3:
 

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Discussion Starter #19
I doubt if the top of the gauge is 100C as the coolant can get hotter than that before it boils. But of course it could be as it's not meant to get to boiling point.
Yeh, from memory it was 100 degrees with the gauge up to the very top. But I see what you're saying.. I'll double check this tomorrow anyway..
 

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there's 2 temp senors
one is at the bottom of the radiator you need to take the undercover off to get to it and the other is near the throttle body which looks like a pain to get to

i would check the radiator one first ( easiest and most likely )


bit of a long shot but check fuse 36 under the dash it's related to the main radiator fan relay amongst other things
 
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