2004 Aztek heater blower control

My wife's 04 Aztek's blower control only works on the off position. It doesn't work on any other setting. It blows on off, as if it was on the number 2 setting. She came home today and told me now it doesn't work at all. Is there a switch or something I can just replace, or do I have to replace the whole thing. The hot and cold setting and the other knob work fine just the blower setting doesn't work. Thanks in advance.

I know this is an older thread but it may help others, my wifes 2005 Aztek lost a couple of fan motor speeds, the problem may be a bad speed resistor module, it sits between the blower motor and the firewall, it cost around $30 or so, not too hard to remove but installing is a bear because the two back screws are nearly impossible to get at, I just backed them off enough to slide the slotted new part past them and then tightened the front screw down. You do have to remove the blower motor but its easy.

That is easier and way cheaper than the list $350+ climate control module....which could be the real problem, I think some of the reasons the blower speed resistor is burning out is because the cabin air filters (2) get all plugged up, they are behind a couple of panels in the back of the glove box.