I have a 2002 F-150 and when I turn on the ignition a fan noise or something comes on and runs until I shut the ignition back off, the sond is coming from behind the gauge panel it sounds like, I shut the heater off and the noise is still there, is this normal or do I have a problem?

I have a 2002 F-150 and when I turn on the ignition a fan noise or something comes on and runs untill i shut the ignition back off, the sond is comming from behind the gauge panel it sounds like, I shut the heater off and the noise is still there, is this normal or do I have a problem?
Are you hearing a fan noise, or could the noise be coming from the audio system speakers?
Does the noise occur at all road speeds? And in all temperatures?


Please let us know, OK?