NYMUSTANGZ

Hey guys, new member here..

Quick question..thank you so much in advance...

The hot days are upon us and I noticed when I first turn my air conditioner on in my 2003 mustang...

Theres a very very slight (wouldn't have noticed it if i wasnt so paranoid)
humming sound that goes to this sequence _____.....____....._____. etc. etc.

It lasts about 5-10 minutes and then goes away.

I also noticed it's there again when I come back from a drive and put the car in park...but then once again goes away again...

Does this sound normal? Any ideas? Air still blows cold. Thank you SOOO much in advance!!