Some download managers might be able to do that, but it is not recommended.

Please explain the problem in detail. What happens? What is/are the exact error message(s) ?

Thank you, I am currently downloading an ISO file that is taking a while due to internet problems, and my computers fan isn't working and I am getting it checked out. My computer is getting hot and I would prefer to let it cool down and then resume the download.

It is best to use an external download manager if you have issues with downloading files, especially when you deal with large files.

If you pause a download then you should be able to resume the download in Firefox, but if the download stalls or is otherwise interrupted then this might not be possible and Firefox will start the download from the beginning.