In addition to the two pin connector at the motor to the left of the motor mounted to the duct work is a 4 pin connector to the speed regulator. In the under hood fuse box there is a blower relay and a fuse. The blower ground amazingly is on the far left side of the dash. There are other harness interconnect connectors as well. The speed regulator has a thermal "fuse" it might be going out. If you unplug the 4 pin speed regulator connector and ground the Blue/Black wire it should run at full speed. indicating the motor and relay are OK (ignition ON).check the plug connections for the motor. It is located directly under the glove box.