most likely a defective blower module under the hood
The blower motors only work with the engine running. If the blower motor has three wires on the electrical plug, then the blower motor module is built into the unit & it's very expensive. Sometimes, you can tap on the motor with a hammer & it may work or slowly turn. If this is the case, replace the blower motor.
A bad resistor or a bad switch.
on the blower module located on the A/C evaporator case R/S under the hood
the blower motor has gone bad
I have an 03 deville and found my blower motor under the dash on the passenger side. It was intermiitant so I took it out and cleaned it. Works fine but I am planning on getting a new one as the brushes are close to worn out. I would advise you do the same
You may have a vacuum leak
Blown fuse? Bad blower motor? Bad blower motor resistor? Bad blower motor switch?
could be the blower motor, a fuse, or a bad wire.
Could be, a blown fuse, a bad blower motor, a burned out blower motor speed resistor, a bad blower motor switch,
sounds like power feed to blower motor is non existant, and or blower motor is finished. The cycling of the compressor only means cold is being made, but not being blown into the car interior.
Defective blower motor or blower motor resistor pack.
I have the same problem with a 1991 DeVille that I acquired three days ago. The blower worked fine at first, then would not shut off but would vary speed from the dash control. Now it only runs at high speed in the off position. After shutting off the car, the dampers repositions to the heating position from the cooling position. the blower motor has a high amp draw shorting the control module, replace them both!!!!