Blower motor

Shutting off the A/C would not stop the blower motor. Turning off the blower speed would do so. If turning the blower switch to off and motor keeps running, possible cases are : 1. Faulty heater control panel, it is grounding the circuit to keep the motor running... 2. Faulty power transistor. It is shorted to ground... 3. Faulty swittch, it is not turning off.. At what speed does the motor operate when switch is turned off? Are you able to control the fan speed with the switch?