2001 Jeep Cherokee interior heater fan

Welcome to the forum, you may need to get all codes checked, see if anything points at the hvac system. You can check wiring circuits, start at the blower relay, behind the glove box, in the hvac housing. Voltage to load side of relay is hot all the time. Voltage to coil side of relay goes hot when you turn the key. Or you can takes connector loose from blower motor, turn on key and hvac, check for voltage at the connector. If voltage is good, check ground. I believe on and off and blower speeds are controled on the ground circuit. You need to test when the problem is ongoing.