Heater (blower motor)works for 3 seconds then shuts off

The blower motor will sometimes work but for 2 or 3 sec then sguts off and I think only on high. If I turn the ignition key on and off quickly and non stop it will sometims go on for those 2 or 3 sec. Here is what I have tried so far.

My buddy has the same car a 2000 chevrolt cavalier Z24 and so we spent a few hours swapping parts from his car to try to get my heater to work. We changed the blower motor, the heater-A/C controls, the fan blower resistor. There is really nothing much left. I doubt its a loose wire as I pulled and pushed and banged every wire that has to do with the heater.

Anyone have any ideas.