While it’s fine for you to vacuum out a register or clean out any visible dust that you see stuck to an air vent, it’s better to leave this job to the pros. Assuming there is something in there to be cleaned out, be it mold, microbes, or just a lot of dust, you might cause an even bigger problem if you clean the ducts incorrectly. It’s better to call your local air duct cleaning company and have an experienced professional do it for you