HEATER BLOWER NOT WORKING ON 1,2,3, SETTINGS, ONLY 4&5.

There is a blower motor speed module which is located under the dash not far from the blower motor itself, just follow the wires from the motor. The switch is in the climate control head. Fastest way to tell what is defective is to scan the climate control computer and see if the switch is working, the data stream will display the switch, there may also be some codes in the climate control module for what is ailing your heater system. Most parts stores don't carry a climate control capable scanner, by the way.