Accordion IE11 help

Accordion IE11 help

I have inherited website from a previous employee and I am still learning web development. IE 11 came out and broke my accordion on the site. I have tried for days to find the solution but I am having trouble following all the code and understanding which scripts are actually doing the work and maybe failing. the site is jprofleetproducts.com the menu on the left side is what is broke and works in firefiox and chrome not IE 11 but does work in IE10 and below.