Driver's side doesn't heat but passenger does

[Caraduras]

Just a follow up note. I did find my climate sensor. It is between the radio and the far right dashboard switches. Looks like a small vent the same size as the switches and the farthest right in this array. I cleaned it, but no change.

Lee was right on. It turned out to be the driver's side tempature damper motor. It requires a dashboard removal and runs around $450 to get fixed. Thank you all for your input.