C5 Cooling Fan Running Continuously.

[ACF]

Hi,

I have a 2008 C5 1.6HDI. I went on a one week holiday a few weeks back and ever since I returned to pick my car up at the airport the electric cooling fan has been running. As soon as I put the key into the ignition the fan starts to run, I don't even have to turn the key. This is happening even first thing on frosty mornings. When I turn off the engine the fan runs on for about 30 seconds and then stops.

Everything else on the car seems to be working fine. Has anyone any ideas what the problem is. I suspect a faulty temperature sensor but haven't a clue where this is located or how I can test it.

Hope you can help.

Thanks.

[paul.h]

Welcome to the forum.

 

If you have the aircon switched on, try turning it off to see of this makes a difference. The cooling fan has to run if the aircon is on.

 

If it is the 2004 to 2008 C5 version, according to the Haynes manual, the engine temperature sensor is in the coolant outlet housing at the left end of the cylinder head. This is the only temperature sensor on the coolant and is used for the temperature gauge, cooling fan and engine ecu. If it is indicating a high value then these other things will also be affected. If you have a code reader that also gives live data, you will be able to see what temperature the sensor thinks it is and then decide if it is faulty and needs replacing. A new sensor will only be about £20 so if you do not have access to a code reader you could just get one and plug it in to the electrical connector as a test and see if the fan goes off - if so it needs changing.

[ACF]

Thanks paul h for your post. The aircon is already off, it's very seldom turned on as it has never worked that well.

My C5 is the 2008 - 2013 model, not the previous model. Do you know where the sensor on newer model is located and does the same thing about getting a new sensor and plugging it in still apply as the best way to see what the problem is?

Thanks.

[paul.h]

The temp sensor is the same, in the housing at the end of the cylinder head. It is held in place by a clip and has a seal. The fan is supposed to cut in at 97°C and out at 94°C, with a high  temp warning at 118°C and cut off of the air con at 115°C. The fan has a relay in the loom at the fan, it is probably not faulty since the fan stops after 30 seconds - if it was sticking the fan would probably not stop.

 

Chances are you need a new sensor so plugging one in as a test is probably the lowest cost to get a diagnosis since a garage/dealer may charge £50 upwards just to do one. You can get a decent enough code reader with some live data for about this so is something to consider as a useful tool if you do your own diy on your car. for example http://www.gendan.co.uk/product_GCR25_16.html#product_information The live data is limited but if you want to look at all the car's data you need a dealer type Lexia.

 

What area are you in since some members on here have diagnostic equipment and have said they are willing to help others and there is a pinned post on one of the C5 sections.

[ACF]

Thanks again paul h. I'm based just outside Belfast in County Antrim, don't know if any other forum members in this area.

I think I've located the sensor. The sensor is probably changes resistance as the temperature changes unless it's a thermocouple in which case there will be a change in voltage from it. I have an electronics background so I was hoping to simulate the sensor. Do you know which type it is and do you know the range of the device (it should either be in ohms or in millivolts).

Failing this I'll probably buy a replacement sensor.

[paul.h]

The sensor is resistance based and it reduces as it gets warmer. It has 2 wires to it so you could measure the sensor resistance and try putting a resistor across the connector to see if the fan stops. Do not just unplug the connector to see if the fan stops since you will likely get a fault/warning due to a resistance outside of the expected range. It may be worthwhile checking if the connector is clean/dry.

 

According to the French RTA manual for the mark 3 C5, the sensor resistances are as follows -

 

20°C 6370 ohms

60°C 1244 to 1288 ohms

80°C 632 to 652 ohms

100°C 339 to 352 ohms

120°C 194 to 202 ohms.

 

If the air con is not cooling that well it may be low on refrigerant and just need regassing, about £50 at a dealer.

 

If you are ok with French or a dictionary, the RTA manual is worth having. It is like a Haynes manual and available from such as Amazon http://www.amazon.co.uk/Rta-B737-Citro%C3%ABn-Depuis-2008/dp/2726873758/ref=sr_1_fkmr2_3?ie=UTF8&qid=1385772864&sr=8-3-fkmr2&keywords=RTA+c5+manual

[ACF]

hi paul h, I was just wondering if the sensor does the job for the temperature gauge, cooling fan and engine ecu then why is it faulty for the fan but the temperature gauge is working normally?

thanks.

[paul.h]

Is the gauge not going to a normal position as soon as the engine is started or is it taking a few minutes to get there ? If the tests on the sensor do not show a problem with it then other possibilities will need to be considered.

[ACF]

Hi Paul. The gauge appears to work normally, starts off low and then climbs to just below mid range after driving a short while.

[alan1969]

Hi there just like to no if you got your cooling fan fix.because my car is doing it now .please can you help 

 

I have a 2009 C5 1.6HDI. citroen the  cooling fan has been running. As soon as I put the key into the ignition the fan starts to run, I don't even have to turn the key. This is happening even first thing on frosty mornings. When I turn off the engine the fan runs on for about 30 seconds and then stops.

Everything else on the car seems to be working fine. Has anyone any ideas what the problem is .

Hope you can help.

Thanks.

[paul.h]

Welcome to the forum. I have deleted your other similar topic and included it here so any replies are in the same place.

 

The OP has not been on the forum for 2 years so we will never know if their problem was fixed.

 

Our C3 fan and engine high temp warning recently came on continuously and the dealer replaced one of the engine temperature sensors as a recall had just been issued for faulty sensors on the EP engines. So it may be worthwhile visiting your dealer service department.