On mh 2006 Chrysler Pacifica the blower will come on and go off at random on 2004 Chrysler Pacifica

I will have it set to cool and the blower just stops blowing. And at random if will come back on and at random go back off. What could this be?

Asked by for the 2004 Chrysler Pacifica
I had to change my blower motor it cost me 80 bucks and its 3 or 4 bolts mine would be on shut off or it would make a loud hum noise