Giving washer/dryer a clean out?

[IShallCallYouSquishy]

I want to give my washer/dryer a clean out and not sure what to do. Do I just run an empty cycle or do I need to put a special cleaner in it?
Is this something that trusty white vinegar can do?

Thank you!

you can buy cleaners for them at the supermarket, but I just run mine on a 90 degree was once a week to keep it clean, my mil puts some dettol in her's.