Radiator Fan operation

[Tizzy]

Hi All

I’m maybe being a bit paranoid, but should I be able to clearly hear the front radiator fans in operation? I can’t remember from when I had a 996 before if they were especially loud, but on my Wife’s 991 you can certainly hear them kick in. Listening at the front intake there’s no obvious noise of operation. The temperature gauge isn’t going above normal when driving and even if the car‘s stationary for a while with the engine on it doesn’t seem to overheat (engine compartment fan comes on quite audibly). Like I say, maybe they’re just quiet and I’m being dumb!

Many thanks as always!

Chris

 

[terryuk]

Hi Chris

I have a turbo and I can't hear mine either. Engine purge fan definitely.

According to the Oracle (Porsche 996 The Essential Companion by Adrian Streather), firstly you won't hear the fans when the engine is off.

For 3.4 and 3.6 standard engines the fans are two speed and operate at low speed when either the air con is turned on or when coolant temp reaches 96.75C.
The fans switch to higher speed when coolant temp exceeds 102C or the air con system over pressure switch closes at a refrigerant pressure greater than 16 bar. Please don't ask me what the last bit means!

Hope that helps.

Regards
Terry

 

[Tizzy]

Cheers Terry - my A/C isn’t working at present (needs new condenser rads) so maybe that’s a factor - also I don’t think the temp gauge has ever gone as high as 102C (usually sits in the middle at 80 something) so maybe I’m worrying unnecessarily ??

 

[andywill]

Hi All, Below is what the fans should be doing. I think this is regardless of the state of the A/C (ie if system is discharged).
It’s not uncommon for the resisters to fail these are located low down at the rear of the rad fans. If you think you have a problem with them the the link below explains how these can be tested.
From the 1999 Porsche Carrera Service Information Book
Quote:
1908 - Electric fans
There are two radiator modules installed in the front of the vehicle (on the left- and right-hand side). These radiators are each fitted with an electric fan. They can be operated at two speeds and are activated by the DME control unit whenever the following conditions apply:
Electric fan, speed 1
(Ground to DME control unit, terminal 35)
Coolant temperature higher than 96.75°C or air conditioning switched on.
Electric fan, speed 2
(Ground to DME control unit, terminal 36)
Coolant temperature > 102°C or air-conditioning fluid pressure switch closed (coolant pressure > 16 bar).
Note: The electric fans for the radiators are only triggered when the engine is running!
There is only one control line (via the DME) so they switch on together.

http://911uk.com/viewtopic.php?t=127681
Good luck
Andy