Car Paint problem

when I edit the part marked on the uploaded image the car paint became from red to this strange effect, it seems a car paint mixed with pure glossy.
Anyone know something about?

It is pure glossy, coming from the last mix before material output.

Yes, you’re right, in fact if I take away it the problem show off, but I need it, it takes the key-effect.

Oh, I got what’s the problem: in setup material the layer weight node was set up as fresnel and not as facing.