You cannot make an AJAX call from an HTTPS site to a HTTP site on a local IP address.

One of the internal web applications I develop (which is hosted over HTTPS itself) has to workaround this by doing the connection from the browser to the local IP address over HTTPS, but upon detecting HTTPS cert errors it opens a popup and walks the user through the process of adding an exception to connect anyways. Once that popup closes, then the AJAX request gets retried and succeeds.

While this works for an internal application, it would be unacceptable for any consumer product.