I have a wind vane that I purchased a couple months ago or so and just deployed outside. I'm finding that it has deadspots in the readings. There are 2 arcs that read 3.3V and 2 arcs that read 0V and they are each about 15-20 degrees each. One of them is from 189 degrees to 172 degrees which is pretty much dead south.
The angles may not be exactly right because it's a bit difficult to get the exact angles with it mounted on a pole.
Am I doing something wrong or do I just have a faulty vane?
Did you look at the specification about what voltages are supplied? At 3.3V there isn't a lot of difference between the voltages. Compare the voltages to the spec and report back and we can take a look at it.