# Radiator Fans



## NickG (Aug 15, 2013)

I've got a little concern that my fans aren't working, can anyone tell me:

1) what the protocol for the fans turning on are, do they come on together at a certain temp?

2) how can I test this short of running the car above the above temperatures somehow?

Thanks!


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## YELLOW_TT (Feb 25, 2004)

With the air on both fans should run at slow speed


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## NickG (Aug 15, 2013)

I see! I've removed the AC, so I wonder if this would effect anything?

Embarrassingly I never actually used the aircon before it was removed either, so I'm not 100% sure I know how to turn it on? 

Am I right in saying the Econ button should be off?!


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## David C (Apr 15, 2013)

With the AC off, the low speed are triggered by the temperature switch on the rad.
Low speed can be triggered with the ignition off and is just a basic circuit.

High speed can also be triggered by the rad switch, but that triggers the fan control module, which then turns the fan on.
High speed can only run with the ignition on.


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## infidel.uk (Feb 21, 2015)

I am planning on replacing both mine with a couple of kenlowe fans , then add my own switch , completely over riding the control module, ill figure it out as i go. :?

IF there is room i might even add a small one on the front as well, or might have to do just that instead, ill see what happens when the time comes. :lol:


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## 3TT3 (Aug 30, 2014)

standard operation for me:
turn ac to auto/econ no fans on at normal temps
If engine gets hot say 100C or so the rad cooling fan comes on.

Set a/c to auto and both fans come on


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## Madmax199 (Jun 14, 2015)

Nick, with ignition on, just pull the plug and jump the pins on the thermostatic switch mounted on the radiator. It's a 3-pin switch and one bridge should have both fan fire at low speed -- bridging the other circiut will have both fans running at high speed. This is the best and easiest test to find out the fans are operational. Cheers!


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## infidel.uk (Feb 21, 2015)

ive just been playing with my car and it seems that when the temps get high, both fans come on, and they also work with the AC on.

Ive only seem them run at one speed though, can anyone please advise. ? :?

Also i don't think my after run pump is working as it should, but i can test this with a direct feed later i guess. ?


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## David C (Apr 15, 2013)

infidel.uk said:


> ive just been playing with my car and it seems that when the temps get high, both fans come on, and they also work with the AC on.
> 
> I've only seem them run at one speed though, can anyone please advise. ? :?


That is probably the low speed mode then.

What temperature are you seeing when they run with the AC off ?


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## infidel.uk (Feb 21, 2015)

94c

ive already got a fan control module on my watch list on eBay . lol


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## Madmax199 (Jun 14, 2015)

infidel.uk said:


> ive just been playing with my car and it seems that when the temps get high, both fans come on, and they also work with the AC on.
> 
> Ive only seem them run at one speed though, can anyone please advise. ? :?
> 
> Also i don't think my after run pump is working as it should, but i can test this with a direct feed later i guess. ?


See my other post for testing the fans/motors at both speed. Jumping pin 1 and 2 with ingnition on will operate both fans at low speed. Jumping pin 2 and 3 will have both fans operate at high speed.










For full diagnostic follow the steps below:

*"
1. To test a fan motor, unplug the electrical connector at the motor and use fused jumper wires to connect battery power and ground directly to the fan. If the fan does not operate, replace the motor.
2. If the motor tests OK, check the cooling fan thermo switch, located at the bottom of the radiator on the driver's side.
3. Remove the electrical connector from the cooling fan thermo switch and apply a fused jumper wire between terminals number 1 and number 2 with the ignition switch in the ON position, with the engine not running. Both engine cooling fans should run at low speed.
4. Next apply the fused jumper wire between terminal number 2 and number 3 with the ignition switch ON and the engine not running. Both engine cooling fans should run at high speed.
5. If the fans run as described in steps 3 and 4, it indicates that the cooling fans and circuits are running properly and the thermo switch is faulty.
6. If the fans do not operate with the thermo switch bypassed, check for voltage at the red wire of the thermo switch electrical connector. There should be battery voltage. 
7. If voltage is not present check the large cooling fuses in the engine compartment fuse holder and the No. 16 fuse in the passenger compartment fuse box. If the fuses are OK, the problem lies in the wiring harness, the fan control module or the coolant temperature sensor.
8. Check the wiring for open or short circuits. The fan control module can only be diagnosed as faulty through process of elimination"

*


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## infidel.uk (Feb 21, 2015)

sweet, ill try this 1st chance i get , thanks pal !


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## Jez xbx (Oct 24, 2014)

Morning all!
A little assistance if I may? 
Stock 225 APX manual roadster

So, I think my fans have stopped working.
Previously I believed I had an issue with the low speeds not working
Tested with engine running, aircon on, no low speed fans
However, every 45 seconds or so high kicked in for about 10 seconds (both fans)
This was occurring at about 95ish on 49c which seemed a bit weirdly low?

Recently, on motorway run noticed temp steady at 94 on 49c (usually about 90 on the nail)
Then in traffic, temp hit low 100's and finally parking had got up to 108.
(Both the dash pod and 49c were in agreement btw)

So I'm diagnosing this as complete failure of the fan system.
I'm guessing my low speed resistors might have gone a while back? 
And now something else has died too?
I've checked the fuses on top of battery, and seem OK, and pulled fuse 16 which seemed OK.

So I'm now trying to test the different bits of the fan system following Max's guide
But I'm having a devil of a job getting to the connectors?
I've removed the battery, battery box, air box and s shaped boost hose off the inlet
I think I finally found the triangular thermo switch on my passengers side below battery / air box
Mines not on the drivers side for anyone else looking!
Also down there is a black box I'm guessing is the fan control module? 
And near the bottom I've found the two electrical connectors for the fans themselves?

But after several hours exploring I'm stuck
I'm really struggling to figure out how to pull the connectors apart?
Any tips? I think I've already cracked part of the fan connectors and don't want to do more damage!
Am I better off trying to remove the big fan? (Is this even possible?)
Or should I drain down the coolant?
Or remove the boost bar across the bottom?
Or the bumper?
I'm doing this on the street btw but have the wheels on the kerb so can get under

Any assistance would be greatly appreciated!

Jez


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## Hoggy (May 8, 2002)

Hi, Can't help with disconnecting plug, but 100 in traffic is not overheating as long a fans cut-in.If you then park up then temp will continue to rise because of the heatsoak effect & no flows, there is a tremendous amount of under bonnet heat.
I would have left engine running open bonnet & checked if fans where running, if so temps would have lowered.
Hoggy.


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## Jez xbx (Oct 24, 2014)

Hi Hoggy I did check when stationary with eng running
No fans and 108 on c49!

Also, can anyone tell me how to test the fans?
Currently I've taken a connector off the bottom of the fan control module?
Put 12v into each of the connections on it and neg on fan body but getting no fan action?
:-(


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## David C (Apr 15, 2013)

Jez xbx said:


> Also, can anyone tell me how to test the fans?
> Currently I've taken a connector off the bottom of the fan control module?
> Put 12v into each of the connections on it and neg on fan body but getting no fan action?
> :-(


Have you tried shorting the pins on the rad switch connector?
(obviously you'll need to reconnect the FCM to get the high speed to work)


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## Jez xbx (Oct 24, 2014)

Hi David,
I did try but reading through the testing thing I felt I needed to establish if the fans were running first.
Max's excellent instructions require you to know the fans are running as I understand it
But with the battery I couldn't get them to work. :-(


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## Jez xbx (Oct 24, 2014)

Ok update time
Seems my fans will only run ......
At high speed (no slow speed at all)
Pulse so run for about 5 seconds every minute (quite regularly according to my lap times lol)
Will only run if air con is on (aircon off temps can get to 108)
Run regardless of temperature (fans started about 1 min after starting engine with 49c at about 24 degrees)
Any ideas????????????


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## newrayTT (Feb 6, 2013)

Jez I think I told you that I recently replaced my big fan as the slow speed was not working. Hate to tell you but it took me about 2 hours to disconnect the connector. As you probably found its in a real pig of a place But there is a small tab to press to release the connector but I found that I had to first release the connector from a sort of square housing that fits in a groove in the connector. It is pretty difficult to explain but I think you are right to try and check out the fan function first if you can.
Good luck mate, I was not sure what was the problem only that my big fan wasn't working and after reading all the available info I decided that the easiest thing to start with was to replace the fan. I believe that if you pull fuse 16 the low speed should run and if it doesn't then the resistors have failed.


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## Jez xbx (Oct 24, 2014)

Hi Ray, pig of a job is an understatement!

I found the connectors you mention but couldn't get them apart.
I see what you mean about lifting them out of the grooved holder before separating.
I didn't manage that and in trying to separate them i cracked one of them :-(
So I stopped before I did any more damage! Just hoping the bit I broke is on the fan, not the wiring loom!

Next I tried feeding power through the connector that fits into bottom of fan control module.
I figured this was the next connection 'upstream' from that one.
However, I couldn't get fans to move doing this. 
I guess I need to pull that cracked connector apart to test properly 

My current thinking / analysis is as follows......
There seems to be no low speed action from any of the potential triggers 
thermo switch low level circuit, thermo switch high (via FCM), aircon (via FCM?) and pulling fuse 16 (via FCM?)

The high speed fan motors are functioning in that both will spin up under the right conditions.
With the aircon on, the fans run irrespective of engine temperature. (from cold startup and onwards)
The fans run for about 5 or 6 seconds every minute, regular as clockwork?
On tickover, the system stabilised with the temp oscillating between 92 & 94 yesterday in the sunshine

However, with the aircon off, the temp will rise to at least 108 (I lost my nerve and switched off at that point!)
No fans were kicking in.

So.....
First off, I'm fairly sure the coolant temp sensor is fairly accurate, 
It was reading about 70ish before replacing the thermostat, now quotes 90ish on a long motorway run at 75ish mph

I'm pretty sure you're right about the fan low speed function being fried as nothing makes them fire up.
This suggests at the least I need a new set of fans?

What's puzzling me is the intermittent high speed seems to be triggered by the aircon????
As I understand it, regardless of aircon, above 104ish then the thermo switch should trigger high speed fans via the FCM?
I'm beginning to think I should just bite the bullet and replace all the bits...
Fans, FCM and thermo switch.

What else is there in the system to change??? lol
Sorry for the long post, it helps me write all this stuff down and mull it over!

PS Ray, did you get to the connectors from above or below?
And did you have to drain coolant or did you get the fan out without? 
And out through bonnet or through under tray???


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## Hoggy (May 8, 2002)

Hi, Until you can bridge the connectors on the thermal switch I wouldn't replace anything yet.
Hoggy.  .


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## David C (Apr 15, 2013)

Hoggy said:


> Hi, Until you can bridge the connectors on the thermal switch I wouldn't replace anything yet.
> Hoggy.  .


I think he may have tried that:


Jez xbx said:


> There seems to be no low speed action from any of the potential triggers
> thermo switch low level circuit, thermo switch high (via FCM), aircon (via FCM?) and pulling fuse 16 (via FCM?)


If he hasn't tried that then yes he needs to ASAP.

This bit I find odd though:


Jez xbx said:


> The high speed fan motors are functioning in that both will spin up under the right conditions.
> With the aircon on, the fans run irrespective of engine temperature. (from cold startup and onwards)
> The fans run for about 5 or 6 seconds every minute, regular as clockwork?


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## Jez xbx (Oct 24, 2014)

David C said:


> Hoggy said:
> 
> 
> > Hi, Until you can bridge the connectors on the thermal switch I wouldn't replace anything yet.
> ...


Hi guys, thanks for the replies
I've not tried jumping the thermal switch yet.
When I took the car apart I believed the fans had stopped working completely. (108 on the display and no fan action!)
Furthermore, I couldn't make the fans spin up using jumpers from the battery directly.
So not knowing if the fans were functioning I decided not to proceed.
I don't think you can draw conclusive results unless you know the fans are functioning?
Now I know the high speed is working I will try jumping the thermal switch to see if that triggers it.

yes it is odd, I can't find any info on what might be causing that?
It would appear to be Aircon via ECU via FCM instigated?
Switching the aircon off stops it functioning?????


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## David C (Apr 15, 2013)

Jez xbx said:


> I've not tried jumping the thermal switch yet.


Hmm.
That should have been one of the first things to try as it is the primary trigger for the fans.


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## newrayTT (Feb 6, 2013)

Jez, I disconnected the electrical connector feed from below and removed fan from the top. However this was only the large fan and it looked to me as if the small fan would be more difficult. Yes I drained the coolant because it was necessary to release some pipe work plus the air feed pipe to the inlet manifold to make enough room to get the fan out.


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