I have a 2005 Santa Fe, 125,000km, and since the last 2 weeks my blower only works on the highest speed setting. Doesn't matter whether I have AC on or not. I'm getting told it's either the resistor or the switch. Now, nothing has hit and banged the knob and it still feels exactly the same when turning to the speed positions....nothing feels out of the ordinary, so I have a hard time believing it's the switch.

Anyone have any thoughts in this?

You have been told correctly, it IS either the resistor or the blower speed switch. You won't necessarily be able to tell if the switch is bad by how it feels, they go bad quite often, as do the resistors.

Thanx LilBean. I think I'll try replacing the resistor first and see how it goes. Replacing that cost way less than the switch.

Might look bad, but can't you replace the switch with something after-market. Maybe, bypass thru relay and attach the after-market switch elsewhere. (Due to high cost, you mentioned)

Apparently the fan switch is a common failure item. I'd recommend visiting a junkyard or (if your car is under warranty still), your dealership.