I changed my heater core. In the process... every brittle plastic panel you have to remove to get to it broke into pieces. I was able to salvage the one that the heater core itself mounts into and get it secured into place. Now when I turn on the heat and try to switch it from vent to defrost ect.. nothing happens. It just blows hot air from the void where panels use to be. My question is.... Is it possible that those panels work as some sort of ducting system to direct the hot air where it needs to go? or is it my control selector valve? I checked the vacuum lines to and from the selector valve and they all appear in tact. any help is appreciated.

 

Yes, those doors are what divert air through the heater core. Without them, the air just goes around it.