One of the more important properties of an autoclave and one which is often overlooked is that it breathes. Throughout the cycle air and steam enter and leave the chamber. In the initial phases, air is exhausted to be displaced by steam which builds up pressure. As the cycle completes, the steam is exhausted allowing the chamber to de-pressurize and allowing drying of instruments to begin.
I've mentioned the importance of routine maintenance many times, one of the key components that needs to be changed routinely is the bellows. In most sterilizers it is the bellows that primarily allows the chamber to breathe. Most practitioners are unfamiliar with a bellows and likely couldn't even identify the bellows in their autoclave.
Shown above is a bellows kit for a Tuttnauer which includes several components in addition to the rubber bellows itself (indicated by the arrow). The Tuttnauer bellows assembly is found within the door which is unusual as most bellows are amongst the various components within the sterilizer case but not necessarily "hidden" as such.
Bellows can be made of many materials, most are brass, bronze or even aluminum on the exterior. Familiarize yourself with your sterilizer, locate the bellows and make certain it is replaced along with the door gasket and filters as part of your routine maintenance. You can get "preventive maintenance kits" which include all the necessary components including the bellows to help simplify your routine maintenance (RPI is a great source for these kits although often the OEM has them as well). For most makes and models, replacing the bellows and related components should be an annual routine (some require more frequent maintenance, however). If uncertain of how your sterilizer is equipped or what the routine should be, feel free to reach out to me and I can advise you and/or provide links to the manufacturer's recommendations.
The bellows may be one of the most important parts you've never heard of in your autoclave.