Front blower motor for ac? on 2006 Jeep Commander

I just replaced the front blower resister and only the high level is still the only thing working. the replaced for the reason for all level will work. My question is what else can ccuz it to not work.

Asked by for the 2006 Jeep Commander
Have you inspected for Blown fuse? Poor connection/corrosion? No input signal seen from fan command switch?