So Hi.
This line of code.
door.transform.rotation = Quaternion.Euler( 0, 0, 0);
Will give my object the following vector (90, 0, 0);
The next line of code
door.transform.rotation = Quaternion.Euler( -90, 0, 0);
Will give me the Vector3.zero.
My question is, if Quaternion is added by default a 90 degrees to the x axis, because if I go with Quaternion.Idenity it will add too. Or is this a bug of Unity5