I have a harbor breeze ceiling fan with remote. The remote no longer operates the light off/on, only the fan. If I obtain a new remote control unit, do I also have to replace the receiving unit in the fan itself or should it work off the new remote?
Thank you.

DIP numbers must match. Just replace the whole thing BUT first read the manual, some resets are easy.

I have to agree with resetting your remote first. The manual can show you how, and also checkout these very good videos for some pretty good insights, and ideas.

https://www.youtube.com/watch?v=HNJpnAZYCxI