Whirring fan noise behind air bag on passenger side

[Guest]

I have just been away for a month, started my 996 1998 carrera 2, let her run up to temp, and gone out for a spin, parked up, turned it off, and what can
only be described as a jumbo jet engine, whirring fan noise, has now started, and seems to be coming from behind the air bag on the passenger side. When
I turn the car off, it whirrs down, until stop, then when starts up, whirrs up to speed and is a constant noise.

Whats behind that space, fan wise, or something that would make that noise.

Also tapping engine, had for a while, stays there when warm, doesnt go, Im going to take into UNIT 11, and get them to look at it, but seen on one of the threads a loose spark plug, so Ill get them to check that as well, fingers crossed.

Thanks for any help

 

[Richard_Hamilton]

The fan noise is probably the fan for the interior temperature sensor, which is located just below the left hand air vent.

 

[tirfor]

I believe that under the passenger airbag, the heater matrix and fan is located. Try starting the car and switch of the heating fan via the heating control panel, if the noise is still there then Richard's idea is most likely the problem.

 

[Richard_Hamilton]

On my car the sensor fan runs even with the aircon switched off!

Edit: I think tirfor is correct, in that the heater fan is behind the airbag. I was looking at the workshop manual when I wrote that it was on the driver's side - but the manual shows LHD cars.

 

[Tool Pants]

There is a temp sensor fan there. You can see it if you pry off the round grill. On my 1997 Boxster the fan is on when the ignition is on. It makes no difference if the heat or a/c is on or off.