AutoBlog HTTPS Mixed content issue

The issue is related to https://www.car****.co.uk/about

Accessing any of the posts, it will display a link on the top. Clicking on it should open in a popup, but the link is trying to pull data from HTTP rather HTTPS and it's breaking the site.

Is it possible to force all requests to be https? Would like to change this in the code rather than use a plugin like Insecure Content Fixer