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Fan not running after turning off engine

JamesBall

JamesBall

Member
After even "spirited" drives, the cooling fan doesn't continue to run after I have turned the ignition off. If I turn the ignition back on, the fan kicks in and belts out warm air, but stops again when the ignition is turned off.

Assuming that this is not correct (!) can anyone advise me a possible cause? I am guessing a temperature sensor somewhere but then if that had failed, why would the fan start when the ignition is back on?
 
I assume you mean the rear blower? In which case, I've never heard mine carrying on blowing with the ignition off either. Even after I've come off track when the car will be even hotter than after a spirited drive.

I think I'm right in saying that if the temperature sensor in the plenum near the blower fails, the blower will stay on all the time which is the opposite to what you're seeing so I don't think you've got a sensor problem.

I'll have to dig out my Streather book to see if there is any other info that might help.
 
Steve. I am a bit ignorant of both the mechanics and terminology I'm afraid but yes I think it is the heater blower top, rear left of the engine bay (as you look at it from behind the car).

In a "normal" car, when you stop and the engine is hot the radiator cooling fan runs after the ignition is turned off to continue to cool the engine/stop it getting too hot now there is no airflow through the radiator.

Should a 964 not do something similar?
 
James, I believe it should and that function is linked to the relay that is in the panel next to the blower. However, I don't know what sort of temperature it will activate at. It might only happen at extreme temperatures. As I say I've not noticed it happening on mine but I'll check the Streather book for more info when I can.
 
James, by coincidence this thread has just popped up on Rennlist:

http://forums.rennlist.com/rennforums/964-forum/711372-how-long-does-engine-cooling-fan-stay-on-for.html

 
James, the info from 'the book' is that the blower should remain active for 15 minutes after the ignition is turned off. If the NTC sensor detects more than 40 degrees C then it should run in low speed until the temp drops. It should run in high speed if it detects more than 75 degrees C.

My own experience and many of those in that thread above is that the blower doesn't run when the ignition is turned off and I can only guess that is because the temperature in the plenum rarely gets above 40 degrees. Possibly because the main engine cooling fan which serves the plenum is very efficient.
 
Following the very helpful advice above and reference the "Streather book", I have invested in my own copy. What a tome!
 
Disconnect the NTC to see if it works, should fire the fan up straight away.

I've had mine running a couple of times, but it has to be really really hot, I was stuck in traffic at Rouen one trip to Le Mans, on a 40degree day..



Kevin
 
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