Hello, your problem is being caused by a defective blower motor resistor assembly. This resistor is what controls the amount of voltage that actually goes to the blower motor after the control panel switch is set. When you replace it, be sure to check for bad or burnt connections to it as well. They have been known to get pretty hot and burn the contacts in the plug in connector at times. Instructions below. Thanks
Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
Tighten Tighten the screws to 1.6 N·m (14 lb in).