because if the temperature is on high, you can feel slight heat coming out. it does not blow, but more like putting your hand over a radiator, or fire. and the same if the temp is turned down low, feels like putting your hand in a freezer! hehe.
you can't hear it blowing. i had someone have a look at it for me, and they said that they could tell that the blower motor wanted to go, but couldn't. i dont know much about cars, and the guy keeps saying he'll find something for me, but never does! i cant afford to pay professionals, im a student!
Cheapest place for a blower motor I have found is my local scrappy.
Depending on the fan motor arrangement, it could also be the control electronics attached to the motor. Generally a scrappy will sell you the whole lot as a unit. It is also much easier to fit that way!
As most electronics engineers will tell you, all electronics contains a special magic ingredient - smoke. It is well observed when the smoke leaks out, the electronics no longer works!