05 RX8 heater blows cold air driver side

passenger side vent blows a little warm, middle vent and driver side vents blow cold. both heater core inlet and outlet tubes under the dash are extremely hot. I used the diagnostic feature (with the radio buttons) to test the temp control switch and it moves from 1 to 16 one click at a time like it should. anyone had experience where the diagnostics worked but the control switch was still bad? Is there a way to test the blend door actuator?

found the actuator on the driverside. it moves with each type of change by the temp control switchs so the actuator appears to work, i'm gonna change out the air cabin filter before giving up and going back to another dealer. I'm still not buying what the closest Mazda dealer told me that it was the heater core needed flushing. If that were the case, I don't believe the inlet and outlet ports would both be so hot.