Cusser
+1y
Now the blower resistor is only if the issue is that the blower motor runs only on high speed. I'm assuming that's the issue because you say you swapped out the switch itself.
Because if your issue was that the heat is always 100% hot, that would be different, like a bad cable, heat control switch, or diverter door. You didn't specify which switch you changed. Clearer explanations can oftentimes help.