2006 C5 cooling fan

[joepye]

Just had a new condenser/radiator fitted to the air con on my 2006 C5 (petrol engine). The engine cooling fan now runs at full speed and not half speed, as I remember previously (although it did cut back to half speed once when out this morning but then back to full speed. Has anyone experienced this before and know why this is happening since the new part was fitted, and how to rectify.

[GiveMeABreak]

The fan works to cool the radiator and also the air conditioning condenser - The fan will always kick in when the AC is operating, but the speed it operates at will be dependent upon other factors like the engine temp. too. As long as it is working ignore it - the system should adjust the speed as necessary.

[joepye]

Thanks Marc - I can understand if the engine has reached temperature, especially the heat we've been experiencing these last few days. I'm concerned that there might be a problem as it runs at full speed from a cold engine, so nothing to cool down.

[GiveMeABreak]

That will be the Air Conditioning then. It is designed to run when the AC is engaged. As a test, when the engine is cold, lift the bonnet and switch the AC off - the fan should go off and as soon as you hit the AUTO or switch the AC button ON it will immediately switch the fan on.

[wurlycorner]

Don't know if the facelift C5 is different to the s1, but... I've found that even when A/C is on, it doesn't run the fan continuously on mine most of the time - it cycles it in and out as needed to keep the output from the condensor at suitable temp (must admit, I haven't checked how often it's on in the current temps, it may be on continuously at the moment I guess...)

[GiveMeABreak]

Certainly on the C5 MK II, the C3 and the X7 the fan engages immediately the AC is on Iain, and I know the OP has a MK II, so should do the same.

[white exec]

SFAIK, switching on the AC should immediately bring on the fan(s) at slow speed. Fans will only jump to high speed when coolant temp climbs, so with a cold engine, this shoudn't happen.

[xantia_v6]

SFAIK, switching on the AC should immediately bring on the fan(s) at slow speed. Fans will only jump to high speed when coolant temp climbs, so with a cold engine, this shoudn't happen.

The fans will also run at full speed with a cold engine if the A/C system pressure (which is generally proportional to condenser temperature) gets high. This can also happen if the A/C system has been over-filled.

You really need a diagnostics session to read the parameters and see which one (if any) is triggering the unusual fan operation.