There is no power go to the motor. Test the wires to see if there is power to it.
fuse, wiring, blower motor, blower motor switch, blower motor resistor
Check your blower motor relay!
Blown fuse? Bad switch?
Blower motor control relay under dash behind blower motor is bad or has water in it from cabin filter port.
On 03 silverados i belive the blower motor relay is internal to the blower motor resistor. i could be wrong though, check the underhood fuse/relay panel for one.
If you have no blower speeds at all check the fuse, then check the blower motor switch and electrical plug for a melt down situation, then check the blower motor itself.
Defective blower motor switch, or defective blower motor resistor pack.
Blown fuse, defective blower motor resistor pack, defective blower motor, or defective fan speed switch.
check for voltage at the blower motor on all settings. if no voltage check the blower motor resistor or relay. if it has a resistor it will be right beside the blower motor, if it has a relay it will be the relay on the firewall under the hood.it will probably have a purple,orange,blue,and black wires.
"nothing comes out"... Hmmm... That could be the blower motor.Check fuses and possibly have to replace the blower motor. Not a hard job by the way.
Blown fuse, defective blower motor, blower motor resistor pack, or loose wiring.
There is nothing wrong with the motor there is something wrong with the switching circuits