Group by taxonomy headers
I had the same problem. You're almost done, but missed some settings ;). You just need to do some Format settings for Views Accordion in your View.

Here are the steps to make your grouping field as the "header" or "trigger" of the accordion action.


Go to  Format: Views Accordion Settings and select Grouping field.
Check "Use the group header as the Accordion header"




Save View. That's it. Now your Grouping field will act as Views Accordion Header and avoids duplicate headers too. 

Hope this helps.