Bought an used Climatronic out of an MK7. Removed old unit from an North American 2015 MK7 SE or Trendline model. Plugged it in, temp level works, heat seats work, rear defrost works, fan speed works, temp adjusts correctly, infotainment systems shows vents and shows when you change the air flow. Problem, I can not control the vents, air only blows out of the front vents, can't change to front defrost or floor vents. Would this need to be activated with an Vagcom setting or an I missing an component? On the back of the Climatronic their are three plugs, my car has A and B not not C, what does C do?