Chrysler Repair: 2004 sebring blower motor problem, blower motor resistor, automatic temperature control

Question
My Dad has a 2004 Chrysler Sebring with the 2.7L gas engine without the automatic temperature control system.
The problem is that the fan (blower motor) doesn't work...at all :( I know there are many problems when the fan works in the high (4) position, but this problem is different.
Here is how it all started:
First the fan didn't work in Low(1) position, but worked in Medium-Low (2) position. Later it didn't work in any position, than it started to work again. After a while (working...not working..working...) it just stopped working for good.
My Dad pulled out the blower motor and started to check for things:
-all fuses are good
-the connector that goes to the motor always gives 12V to the motor(regardless of the fan switch(0,1,2,3,4---all gives 12V), but the ground is missing, which should be there all the time.
-he temporarily put the ground from the cigarette lighter to the blower motor and then the motor was spinning at full speed regardless for the switch. (It ran at full speed in all setting 0,1,2,3,4).
-it looks like the switch "got stuck" in the high (4)mode and the ground got cut(disconnected). That is weird, because when the blower motor stopped working he didn't really used the High setting and not one fuse got burned.

Answer
Hi Zoltan,
The fan speed is controlled by varying the resistance from the 'ground' side of the fan motor to the actual ground (- post of the battery). So probably that blower motor resistor block has burned out in an atypical way, e.g., completely. So simply trace the wire from the blower motor proper to the resistor block on the lower right side of the heater/ac housing. Pull its plug and then remove the two screws that hold in place for replacement.
Roland