Radiator fan doesn't start randomly. New fan didn't solve.

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My Name: chriz74

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Posts: 13
Joined: Wed Aug 19, 2020 1:49 pm
Model: C3 2002-2005, Original shape model
Year: 2002 (02)
Engine Size: 1.4 i
Fuel Type: Petrol
Mileage: 80000
Trim Level: VTR+
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: LHD (Europe)

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Hello, I can't find any solution online for this problem. This car sometimes displays an overheat alarm and the engine radiator fan doesn't start.
I checked with obd 2.. the alarm appears at 97°. Fan doesn't start. So I put a new fan, same problem, it worked after installation and after two days fault occured again.
Does anyone have any idea?
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My Name: C3CAR

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Posts: 2621
Joined: Wed May 04, 2011 10:01 am
Model: C3 2002-2005, Original shape model
Year: 2002 (02)
Engine Size: 1.4 (16v)
Fuel Type: Diesel
Mileage: 140000
Trim Level: Exclusive
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: RHD (UK)
Engine name: DV4 16-valve diesel (90 PS)
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Is yours the engine with two temperature sensors? Worth checking. It may be easier to just have a look on the engine.

One sensor is for the warning (which is working) and the other is for the engine ECU that triggers the fan (that sensor is probably faulty).
My Name: chriz74

Contributor
Posts: 13
Joined: Wed Aug 19, 2020 1:49 pm
Model: C3 2002-2005, Original shape model
Year: 2002 (02)
Engine Size: 1.4 i
Fuel Type: Petrol
Mileage: 80000
Trim Level: VTR+
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: LHD (Europe)

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Only one sensor. I know because I ordered that blue one only to find that it was not present at all.
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My Name: C3CAR

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Posts: 2621
Joined: Wed May 04, 2011 10:01 am
Model: C3 2002-2005, Original shape model
Year: 2002 (02)
Engine Size: 1.4 (16v)
Fuel Type: Diesel
Mileage: 140000
Trim Level: Exclusive
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: RHD (UK)
Engine name: DV4 16-valve diesel (90 PS)
Has thanked: 148 times
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chriz74 wrote: Thu Aug 20, 2020 10:48 am Only one sensor. I know because I ordered that blue one only to find that it was not present at all.
Which engine do you have?
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My Name: Ozvtr

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Joined: Wed Jul 10, 2019 3:31 am
Model: C3 2002-2005, Original shape model
Year: 2003 (53)
Engine Size: 1.4 (8v)
Fuel Type: Petrol
Mileage: 80000
Trim Level: Other
Gearbox: Automatic PRND
DPF: No
LHD or RHD: RHD
Engine name: TU3 (75 PS)
Location: Brisbane, Australia.
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There are 2 sensors (pre 2009?)
1) Green sensor on the top of the thermostat housing. This sensor is used by the engine ECU to monitor the engine coolant outlet temperature. This is used by the ECU for engine management and (if applicable) indicate the temperature on the dash.
2) Blue sensor on the cylinder head behind the air filter mounting bracket and underneath the thermostat housing. This is the "coolant level sensor". I put it in quotes because it doesn't directly monitor the level of the coolant. But if there is no coolant in the cylinder head the head will get hot and trip this sensor.
The two sensors are in series. The blue sensor provides the earth for the green sensor. If the green sensor goes open circuit or the connector is removed or the blue sensor "trips" either the temp gauge will show all the bars or the over temp light will come on (depending on your car model). The blue sensor goes open circuit when the head reaches 120'C.
So, if you are getting random over temp warnings either one or both of the sensors are faulty, the green connector is loose, the blue connector is loose, there is a wiring fault between the green sensor and the engine ECU or the coolant level is low.

If the over temp warning comes on, the engine fan should run.
My Name: chriz74

Contributor
Posts: 13
Joined: Wed Aug 19, 2020 1:49 pm
Model: C3 2002-2005, Original shape model
Year: 2002 (02)
Engine Size: 1.4 i
Fuel Type: Petrol
Mileage: 80000
Trim Level: VTR+
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: LHD (Europe)

Post

C3CAR wrote: Thu Aug 20, 2020 6:06 pm
chriz74 wrote: Thu Aug 20, 2020 10:48 am Only one sensor. I know because I ordered that blue one only to find that it was not present at all.
Which engine do you have?
KFV ... 1.4i Petrol
My Name: chriz74

Contributor
Posts: 13
Joined: Wed Aug 19, 2020 1:49 pm
Model: C3 2002-2005, Original shape model
Year: 2002 (02)
Engine Size: 1.4 i
Fuel Type: Petrol
Mileage: 80000
Trim Level: VTR+
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: LHD (Europe)

Post

Ozvtr wrote: Thu Aug 20, 2020 10:14 pm There are 2 sensors (pre 2009?)
1) Green sensor on the top of the thermostat housing. This sensor is used by the engine ECU to monitor the engine coolant outlet temperature. This is used by the ECU for engine management and (if applicable) indicate the temperature on the dash.
2) Blue sensor on the cylinder head behind the air filter mounting bracket and underneath the thermostat housing. This is the "coolant level sensor". I put it in quotes because it doesn't directly monitor the level of the coolant. But if there is no coolant in the cylinder head the head will get hot and trip this sensor.
The two sensors are in series. The blue sensor provides the earth for the green sensor. If the green sensor goes open circuit or the connector is removed or the blue sensor "trips" either the temp gauge will show all the bars or the over temp light will come on (depending on your car model). The blue sensor goes open circuit when the head reaches 120'C.
So, if you are getting random over temp warnings either one or both of the sensors are faulty, the green connector is loose, the blue connector is loose, there is a wiring fault between the green sensor and the engine ECU or the coolant level is low.

If the over temp warning comes on, the engine fan should run.
No, there is only one sensor, the green one. Alarm appears at 97C , it can’t be a faulty sensor because it’s reading the temperature correctly. At 97C fan should start but it doesn’t. Sometimes it starts, others doesn’t.
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My Name: Arfur Dent

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Model: C3 2002-2005, Original shape model
Year: 2002 (52)
Engine Size: 1.4 (16v)
Fuel Type: Diesel
Mileage: 100000
Trim Level: Exclusive
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: RHD (UK)
Engine name: DV4 16-valve diesel (90 PS)
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chriz74 wrote: Fri Aug 21, 2020 10:12 am
C3CAR wrote: Thu Aug 20, 2020 6:06 pm
chriz74 wrote: Thu Aug 20, 2020 10:48 am Only one sensor. I know because I ordered that blue one only to find that it was not present at all.
Which engine do you have?
KFV ... 1.4i Petrol
Air conditioning or not?
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My Name: chriz74

Contributor
Posts: 13
Joined: Wed Aug 19, 2020 1:49 pm
Model: C3 2002-2005, Original shape model
Year: 2002 (02)
Engine Size: 1.4 i
Fuel Type: Petrol
Mileage: 80000
Trim Level: VTR+
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: LHD (Europe)

Post

Arfur Dent wrote: Fri Aug 21, 2020 10:43 am
chriz74 wrote: Fri Aug 21, 2020 10:12 am
C3CAR wrote: Thu Aug 20, 2020 6:06 pm

Which engine do you have?
KFV ... 1.4i Petrol
Air conditioning or not?
Air conditioning (not working bc there’s a leak)
User avatar
My Name: Arfur Dent

Guru
Posts: 3308
Joined: Sat Jul 23, 2011 3:47 pm
Model: C3 2002-2005, Original shape model
Year: 2002 (52)
Engine Size: 1.4 (16v)
Fuel Type: Diesel
Mileage: 100000
Trim Level: Exclusive
Gearbox: Manual 5 speed
DPF: No
LHD or RHD: RHD (UK)
Engine name: DV4 16-valve diesel (90 PS)
Has thanked: 259 times
Been thanked: 112 times

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chriz74 wrote: Fri Aug 21, 2020 10:12 am
Air conditioning (not working bc there’s a leak)
Thanks,

There are 2 diagrams for the cooling fan control for the KFV/TU3 engine that I have access to.

The one without A/C has a relay, but the one with A/C is more complicated with some solid state device.



I also found the diagrams of the locations for the 2 engine coolant sensors on the TU3/KFV for early cars.

I am going to add them here just because I am sure google will direct people here looking for engine coolant sensors on the C3 :lol:


Engine temperature sensor Citroen C3
Engine temperature sensor Citroen C3
Engine temperature sensor Citroen C3
Engine temperature sensor Citroen C3


I will dig out the fan motor electrical diagram :D
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