A very common problem with Suby fan motors is resistor pack usually located near the blower motor inside the vent to help cool it. Higher resistance=slower speed. Important yes, but it only functions if power is switched to it. If you have a schematic you will also see a blower motor relay. It is not located under the hood next to the A/C relay. It is inside the car on the drivers side, left of the st. wheel. It won't be too hard to recognize. It'll be the one thats hot/discolored.