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Old 1 Week Ago   #1
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Unhappy 2008 1.4 Sport 500 Cooling fan does not work until AC is turned on

Does anyone have a wiring diagram for how the low and high-speed modes of the cooling fan (radiator) is connected?

Looking to find which fuse and relay it is connected to?

The cooling fan only appears to work when the AC is turned on
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Old 1 Week Ago   #2
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Re: 2008 1.4 Sport 500 Cooling fan does not work until AC is turned on

The fan is controlled by the ECU if itís working with the aircon then there is no reason it wouldnít other wise work, there are no separate relays or fuses.

Unless the car is really hot the fan wonít generally kick in, next time after youíve been on a long drive and you get to your destination or home. Pop the bonnet and sit with the engine running for 10 minutes or so, it should almost certainly then kick in (aircon off obviously)
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Old 1 Week Ago   #3
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Re: 2008 1.4 Sport 500 Cooling fan does not work until AC is turned on

Quote Originally Posted by AndyRKett View Post
The fan is controlled by the ECU if it’s working with the aircon then there is no reason it wouldn’t other wise work, there are no separate relays or fuses.

Unless the car is really hot the fan won’t generally kick in, next time after you’ve been on a long drive and you get to your destination or home. Pop the bonnet and sit with the engine running for 10 minutes or so, it should almost certainly then kick in (aircon off obviously)
This was the first thing I tried. The fan definitely only works with the AC turned on!

I left the car turned on, with the AC off and it overheated (dash gave a temperature warning and the coolant started overflowing). I turn the AC on and the radiator fan turns on almost immediately and does not overheat!
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Old 1 Week Ago   #4
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Re: 2008 1.4 Sport 500 Cooling fan does not work until AC is turned on

Does the engine know itís over heating.

Sounds like it need plugging in to MES then you can turn the fans on and off to test them as well as look at the engine temperature the engine ECU is recording.

The simple fact of the matter is that the fan works and it is turning on and off, which is controlled by the ECU In the same way that the engine operates the fan to cool the engine.

The only logical step is the temperature sensor is not working correctly or there is an ECU fault stopping the ECU from recognising the over heat. The latter would be very unusual.
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Re: 2008 1.4 Sport 500 Cooling fan does not work until AC is turned on

Well it definitely boiled so my thought is this, with a over heat warning on the dash, fans that clearly work OK, leaves me to think one of two things, ECU corrupted or is there more than one relay for the fan? IE AC control relay and temp control relay? I've not got my book to look at the diagram.
In the mean time leave the AC on all the time, but then in Australia I'm surprised you turned it off.
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Old 1 Week Ago   #6
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Re: 2008 1.4 Sport 500 Cooling fan does not work until AC is turned on

Cars used to have a temperature sensor in the radiator to activate the fan. Isn't this the case any more? If there is a sensor (which may be visible) chances are it has failed.
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Quote Originally Posted by TrevC View Post
Cars used to have a temperature sensor in the radiator to activate the fan. Isn't this the case any more? If there is a sensor (which may be visible) chances are it has failed.
Doesnt it use the temp sensor that gives the engine temp on the dash as the dash is saying overheating to activate the cooling fan via the ecu?
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Re: 2008 1.4 Sport 500 Cooling fan does not work until AC is turned on

I would have expected an overtemperature sensor to be mounted on the head or the block, as this would operate if the thermostat stuck shut, and in that instance the radiator would remain cool. Cooling fan actuation sensors tend to be on the rad.
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Quote Originally Posted by TrevC View Post
I would have expected an overtemperature sensor to be mounted on the head or the block, as this would operate if the thermostat stuck shut, and in that instance the radiator would remain cool. Cooling fan actuation sensors tend to be on the rad.
There's no sensors on the rad of our 59 plate 1.2.
Remember the fans will run with the ac this is normal whilst the compressor is operating and is separate to the "engine cooling "
Anyone know if there's two relays
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Last edited by John202020; 1 Week Ago at 17:08.
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Old 1 Week Ago   #10
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Re: 2008 1.4 Sport 500 Cooling fan does not work until AC is turned on

Beats me then. Haynes manual?
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Quote Originally Posted by TrevC View Post
Beats me then. Haynes manual?
It's in my shed at home
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Old 1 Week Ago   #12
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So I've had a look at the manual (for the UK 1.2) relay 6 controls the single cooling fan and relay 7 controls that ac cooling fans side so is it possible that relay 6 is faulty?
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More info
with the engine way up to temp or even over, is there a earthing switching signal applied to pin 85 of relay 6? would show +12v normally and 0v approx when the fan is on(ac off, relay installed) also note the feed to the fan goes through a resistor(12 in the picture) if this has failed then again the fan would not operate normally-don't know where this is installed.
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File Type: jpg 20171010_204818.jpg (2.90 MB, 3 views)
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Last edited by John202020; 1 Week Ago at 21:08. Reason: more info
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Old 1 Week Ago   #14
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Re: 2008 1.4 Sport 500 Cooling fan does not work until AC is turned on

Quote Originally Posted by John202020 View Post
So I've had a look at the manual (for the UK 1.2) relay 6 controls the single cooling fan and relay 7 controls that ac cooling fans side so is it possible that relay 6 is faulty?
Checked that both relays are working fine!

Does the manual state what the low-speed resistor no 12 is meant to be rated to? I assume that it is meant to be 1 ohm as per the below. I checked the relay resistance and it was around 1.2 ohm

https://www.fiatforum.com/stilo-guid...-resistor.html
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Last edited by matthewmalone; 1 Week Ago at 06:15.
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Re: 2008 1.4 Sport 500 Cooling fan does not work until AC is turned on

Did you check the relay switches the contacts for the fan? a small 9v battery will operate the relay on the bench, resistor could be a culprit especially in hot climates as it will be used far more, sorry it does not state value. If you know what you're doing, you could feed the fan directly and measure the current and work out the resistor rating and either buy a new one or create a resistor bank to replace it, I had to do this on the wife's old Nissan heater blower motor. A guess at the wattage 40_50w if it drew 6a @1 ohm =36 watts
Based on 6a 4x4.7R 10w resistors in parallel will give you 1.175R total at will run hot as they're at their maximum rating each, but will cost far less ?
Also i would hope the relay contacts are far less than 1.2r as that would cook the relay?
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Last edited by John202020; 1 Week Ago at 08:07.
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