Strange bug in my weather project

hi all
i working on my weather project and i can make a call to the API but i want to make the C to F button …
first here is my code in github : https://github.com/spyshow/weather/blob/master/js/custom.js

if i press on the F/C button it will not do any thing … where is the problem in my code ?

thanks

any one ??? i am really out of ideas

This works when I try it.