On what vehicle :?: Go into your account details and create yourself a signature that includes your car details.
I'm assuming it is a Mav or T2 diesel, if so it has a viscus fan that runs via a pulley on the water pump which is turned by a fan belt. These are supposed to spin freely as the engine runs and only properly cut in when engine gets up to temp. However when it is cold the fan does seem to run until engine warms a little bit, thats when you can hear the roar of the fan when you rev it up.
Jim T
