Noise behind passenger dash with ignition on
 

Hi guys,
I apologise if this has previously been asked/answered. I did search but couldn't find anything.
When I turn on the ignition switch, there is an irregular, slow "fan type" noise from behind the passenger side dash.
I am curious if this is normal i.e. Should it always be on, should it really be a more constant sound/flow/rate and what function it performs.

I am looking into why my A/C does not appear to cool and noticed this phenomena.

Thanks for any help you can offer.
Cheers
Drew

There is a temp sensor for the automatic climate control system behind the round grill on the dash. It contains a fan that pulls cabin air into the sensor.

Cabin sensor fan.
 

Excellent, many thanks.
Is there a way to test this sensor as my AC does not appear to cool, and maybe ths is a factor in that problem.
Thanks again,
Cheers
Drew.

Assistance
 

Thank you.
Cheers
Drew

Isnt it funny how you have to appologize first to keep all the smart A's from from chiming in?

If the Fan sensor still running after turning off the ignition switch and key is out,
ignition switch is bad(but that's another thread issue) just FYI.