After you finish cooking on the Big Green Egg, there will be ash and coals left on top of the grate and beneath it.
At a minimum, you need to take your ash tool and try to get all of the ashes to fall through the grate. You do this by ‘stirring’ the leftover charcoal using your ash tool which drives the ash to the bottom and through the holes in the grate.
If you look through the bottom vent you can see the buildup of ash on the bottom of the Egg.
If it’s more than just a little bit, it’s best to clean it out so that the airflow is not restricted for your next cook. You can use your ash tool to scrape it out through the bottom vent. Some people use a shop vac with crevice tool to do this. Others take the remaining coals out from the grate, lift the grate and clean out the ash at the bottom from above.
I’ve found over the years, that when I’m having trouble getting the temp where I want it, it’s because I didn’t bother doing any of this.
Take my word—you need to clean before you cook!
Note: there may be live coals in the ash. Always be careful with them. It is easy to start a fire.
Here are a couple of different ways to do it: