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Cooling Fan Is This Normal

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Lately I have noticed my cooling fan coming on after the car has been stopped. On a normal drive temperatures around 45, it comes on about 10 times over a period of 10 minutes. I find that unusual because it is not very hot, and it did not do it once in the last two months that I have had the car (04 C4S). I had a PSE installed at the dealer about two weeks ago, could it be that they disturbed a connection during installation. I realize the fan should come on after the car is stopped, but I find this excessive am I wrong.

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  • Admin

Do you mean the front radiator fans or the rear engine compartment purge fan? If it is the engine purge fan then here is the criteria:

Switch-on conditions for engine compartment fan (this fan pulls air into the engine compartment) The engine compartment fan is switched on when the engine compartment temperature is > 176 degrees F or the coolant temperature is > 216 degrees F.

If the ignition is switched off and the engine compartment temperature is more than 140 degrees F, the DME control module remains in readiness for another 20 minutes. During this time, the engine compartment temperature is retrieved every 10 seconds. If the engine compartment temperature is > 185 degrees F, the engine compartment fan is switched on for 20 seconds. If the engine compartment temperature is still > 185 degrees F after this time, the fan remains on for a further 30 seconds.

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  • 10 months later...

Hi all

my 1998 carrera 2 the fun comes on when engine gets to around 90 degrees (normal) but it is very load and only come,s on for about 5 sec then go,off again.

looking at wiring diagram it looks like there is a three speed fan is this right ? and should it go to speed one first ?

Thanks darren :thumbup:

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The fans are controlled in 2 stages (not 3). There is a low setting that is controlled by the DME based on engine temperature. The high setting is also controlled by the DME and the position of the A/C switch. The fans always go on high (on all the time) with the A/C running. Depending on your climate with the A/C off the low speed setting may rarely come on. I live in Northern California and my low speed fans rarely come on.

BTW... GT3 Cup Cars do not have fans at all. The motion of the car is enough to keep the engine cool. They do have larger openings in the bumper though.

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Does the engine compartment fan also come on when the engine is first started? The fan in my 99 seems to come on for ~30 seconds when the engine is first started cold than operates as Loren indicates.


What you likely hear when you start the engine is not the purge fan but the secondary air injection pump (sounds like a Hoover to me). That air pump only runs when the air/fuel mixture needs it to meet emissions. Usually that is at startup when the engine is cold and when the engine comes back to idle - like at a stoplight after exiting a freeway.
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