Why does the Blower motor go on and off on my impala?

i had the same problem on my 04 impla. At times the blower motor worked fine sometimes not at all, it even seemed like something like slamming the door closed would sometimes make it work. Well after lots of fustration I finally found the problem. First you need to remoce the glove box to get to the blowere motor, next you need to check the two wires going into the blower, on the end of the wires there is a plastic end on it that snaps into the blower. On my impala that plastic end had a split on it that caused the wires not to fully contact the motor, therefore not giving it power, after I replaced that piece everything works fine.