2002 Pontiac Sunfire Blower speed only works on high

I recently purchased the above vehicle, and later discovered that the 2 lower speeds on the heater blower do not work. The 2 high speeds work fine. I have had older vehicles with the same problem and they had both a low & high speed relay. I replaced whichever relay was bad. Do the newer vehicles have this same setup? I only found 1 blower relay. Do I replace that, or do I replace the fan speed switch?
Any help would be appreciated.