C5 overheating

[kevino]

hi everybody, I've got a c5 mark 2, 2 litre diesel 138 bhp estate. in the hot weather i as in a traffic jam and the temperature went up without any fan cutting in, the queue cleared and i managed to coast the car to get the temperature down.
Is there a way of checking if the fan is knackered, like directly wiring it to the battery or is this a bad idea?
or is there something else i need to check first? I've checked the fuses and they are ok.
Any advice is greatly received.

[myglaren]

The one on my second C5 was jammed. Poked it with a stick and it was seized quite badly.
The temperature had never fluctuated though, always steady.
Fitted a replacement fan. Never heard it working and there was no difference in the temperature.

[Gibbo2286]

Question is was it really overheating or was the gauge kidding you? A faulty sender in the thermostat housing is common I found on the C5.

[moizeau]

First question, what are you classing as overheating?

[MH123456]

Check the fan is moving freely, if it's needed and doesn't work then the ECU might show the temperature at max with a warning until the fan isn't needed any more. This happened to me when using the car on a hot day to play a travelling game with some work colleagues, they weren't impressed when we had to stop and let it cool down - we lost the game. Replaced the fan with a really cheap one, it worked but was very noisy. Replacing the temp sender is good advice too, I think they're relatively cheap.

[kevino]

First question, what are you classing as overheating?

The temperature needle was at the top and the auto gearbox went into not allowing me to change gear manually.

[kevino]

Check the fan is moving freely, if it's needed and doesn't work then the ECU might show the temperature at max with a warning until the fan isn't needed any more. This happened to me when using the car on a hot day to play a travelling game with some work colleagues, they weren't impressed when we had to stop and let it cool down - we lost the game. Replaced the fan with a really cheap one, it worked but was very noisy. Replacing the temp sender is good advice too, I think they're relatively cheap.

Where is fan temp sender on this model?

[kevino]

The one on my second C5 was jammed. Poked it with a stick and it was seized quite badly.
The temperature had never fluctuated though, always steady.
Fitted a replacement fan. Never heard it working and there was no difference in the temperature.

Thanks for the tip. I'm going to give it a prod to see if it is seized and if it is replace the unit. While I'm at it i think i will replace the temperature sensor if i can find it.

[citroenguy]

Failed cooling fan is rather common on C5's.
Either resistor or realay fault on mk1's or internal fan failure on later models (speed regulator is built in to the fan).
Never seen a sensor fail. But it's located at the back of the thermostat housing.

Will need VIN to se which fan and sensor is correct