Ok, sorry, I didn't explain well.
Here it is the thing. Yes is the surface of the Material where the problem is, and the channels are in the surface. Those that I marked in red in the image are the channels of the surface.
Check the surface your using in that material and make the corresponding changes to the surface. Wherever you find something like dark red or brown or similar to whatever color the surface is after render, change it.
But as I told you before try it one by one so you can know where excatly is the problem and... (everything I wrote before)