Heater fan switch?

Anybody know about the blower switch on a 00 XJ? It is a 4 position switch and the fan only works on the 4th position (highest). I have the switch apart and it appears to be working. The problem seems to be that I am not getting power for the slower speeds to the switch. In other words, the switch is sending the power to the fan as it should but there is no power for it to send on the three lower speeds. I have checked all the fuses (under the dash and the hood). Any ideas? TIA

Blown resistor pack - I don't have the part number but do some searches for that.

Thanks! That is exactly what I needed. Just a little direction.