tuned on heat/defrost ran 15min.shut off on 1997 Jeep Grand Cherokee

cranked to warm and defrost jeep after about 10-15 min we went to leave and there was no nothing running. then came back on bout 15 min later and then shut right back off. what would cause it not to run at all that is the heating/defrost when you turn on fan doesnt even come on tehen it came on for few min. then shut back off HELP

Asked by for the 1997 Jeep Grand Cherokee
Possible blower resistor.