Heater works on passenger but not driver side (2013 CX-5)

A/C worked fine but in winter the heat only works in passenger side , checked all 3 flap actuators all seems to operate , tried using dual mode and turning up heat to max on driver little difference , turn temperature to 15 degrees a/c is fine , cant see if there is a an actuator/flap that controls passenger or driver side . its same for driver side windscreen heater footwell and centre vent. anyone have ideas as to what may cause this?

I can see there are 3 actuators , presumably one is for recycle/external two is left side and one for right side.
 
Did you ever figure this out? I'm having the same issue: AC comes out uniformly, airflow feels the same everywhere, but heat will feel like it's only coming out of the passenger side. Driver side stays cold regardless of what the temperature is set to. Any ideas? 180,000+ miles, so I wouldn't be surprised if the heater core isn't working at 100%, but I'm not sure how that would cause it to only be hot on one side of the car. Thanks!
 
Yes fixed it was able to remove heat exchanger through passenger side and cleaned the exchanger inards , although you can buy an improved one on internet £125
 
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