I cannot figure this one out for the life of me...no heat front the driver's side hvac while passenger side gets hot. With that, heater core has to be getting hot since there is heat on passenger side. Remove blend door motor to manually open and close and that doesn't change the temp. However, do discover the fan output is significantly reduced when the blend door is on 100% heat...both sides get icy cold when in a/c mode with equal fan volume output. So it seems like there is restricted airflow on the driver's side when in heat mode. Could it be a dirty heater core on the driver's side? Some kind of blockage not allowing air to flow across / through the one side of the heater core? If that is the case, do we think the solution is to remove the heater core from the passenger side and clean it?

I am baffled...Thoughts?