Hello and welcome to Just answer.com, Super mechanic here. About your vehicle.
There may be a problem in the blower resistor. Here is a diagram that will help you to find the problem, along with a picture of where the front resistor is located. The relay powers the fuse, which powers the blower motor. The resistor will complete the ground for the motor to come on.
Ya! you did help me. I replaced the blower resistor and voir la! the system is back to normal.