My a/c fan in my 99 escort recently went quit running. I have checked everywhere for the problem to no avail. I tore the head unit out, nothing. I checked all the fuses, nothing. I took out the fan itself and put a battery to it and it worked perfectly. Then, i put it back in and nothing again. Does anybody have and clue what the problem might be? Thanks

Check the fan resistor/ballast or whatever it's called near the fan inside the car (below and to the left of the glove box).