Hello guys. I have a 2004 Punto mk2b, 1.3 Diesel Multijet with a Robotized gearbox. The radiator fan kicks in (starts) everytime I turn on the engine, even in the morning when the engine is cold. I have checked and replaced: the thermoresistor mounted on the fan bracked (new part, OEM). I have changed the relays, checked the thermostat, the coolant temperature sensor works fine, cooland level OK, air bleeding done twice. No errors on the diagnosis tools. Did anyone encounter this issue or has any solution? Thanks!
Technical Radiator Fan kicking in all the time
- Thread starter madalinV
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Technical Radiator Fan kicking in all the time
Hi. Does seem a strange one.
Have you checked what temps the ECU is seeing?
Could be a poor earth on a diferent component making the fan run..
Have you checked what temps the ECU is seeing?
Could be a poor earth on a diferent component making the fan run..
The fan is triggered by the ecu by earthing the relay coil. On the 8V petrol it's a grey wire that runs from below the fuse/relay box, behind the battery and on to the ecu. That wire can get broken. If it goes open circuit the fan will never fire, if it shorts to earth the fan will run all the time.
Are you talking about the very large resistor that gets hot or something else?
If you have the large resistor then you have air conditioning. If the outside temperature is above 5C there is a potential for the radiator fan to run with the engine cold.
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Turn the air con off and see if the problem persists....
. it was one of the first things I have tried.Are you talking about the very large resistor that gets hot or something else?
If you have the large resistor then you have air conditioning. If the outside temperature is above 5C there is a potential for the radiator fan to run with the engine cold.
Hi. yes, I have AC and tried with two different resistors.
Next thing I will try is the AC pressure sensor, which is mounted on the valve(from the AC pipes) and all of it's cables. It seems if it's faulty or has a short to ground, it might trigger a command to the ECU.
If you have the large resistor then you have air conditioning. If the outside temperature is above 5C there is a potential for the radiator fan to run with the engine cold.
Hi. yes, I have AC and tried with two different resistors.
Next thing I will try is the AC pressure sensor, which is mounted on the valve(from the AC pipes) and all of it's cables. It seems if it's faulty or has a short to ground, it might trigger a command to the ECU.
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Disconnect sensor wiring - but ffa dont disconnect the sensors themselves
You will end up in hospitial
Aircon gas is nasty stuff
Illegal to vent to atmosphere too
Ziggy
Hi guys,
the issue was solved in the end. the wires going to the air-con pressure sensor were clipped (see pics attached).
Soldered them back and it is all ok now.
thank you for the feedback!
the issue was solved in the end. the wires going to the air-con pressure sensor were clipped (see pics attached).
Soldered them back and it is all ok now.
thank you for the feedback!
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Is this true? In my country always temperature abouve 28 C except some areas. So should my fan turn on at low speed with ignition on. I am having it right now run always even before cold start just after ignition on
This Punto thread says if the radiator has a resistor then you have/had air conditioning.
https://www.fiatforum.com/punto-ii/441405-what-unit-fan-radiator.html
And claims high speed operation only occurs when you need both air conditioning and engine cooling.
This stilo thread suggests low speed is for engine cooling at half way on the gauge.
https://www.fiatforum.com/punto-ii/39774-how-radiator-fan-controlled.html?p=464019
You can use multiecuscan to check if low and high speed fan is working.
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I did some tests on my Punto. It is almost freezing here. The car was in the 10C garage with the exhaust near the open doors. With A/C off and the radiator hose clamped as the temperature gets to normal the fan is at low speed and then high speed. Using the cabin heater I could then alter the temperature gauge to get the fan to go to low speed or high speed. High speed fan happens within a millimeter or two of normal temperature.
With A/C on and the engine cold and the radiator hose not clamped the fan occasionally comes on at low speed for a few seconds. Even when the temperature gauge is at normal and the fan runs more frequently it was not running at high speed.
I tried a heat gun on the A/C radiator and it made no difference.
It makes sense the A/C temperature sensor can force the fan to run at high speed when the engine is cold if the air temperature is warmer. I will see what happens in the summer.
With A/C on and the engine cold and the radiator hose not clamped the fan occasionally comes on at low speed for a few seconds. Even when the temperature gauge is at normal and the fan runs more frequently it was not running at high speed.
I tried a heat gun on the A/C radiator and it made no difference.
It makes sense the A/C temperature sensor can force the fan to run at high speed when the engine is cold if the air temperature is warmer. I will see what happens in the summer.
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