Back when I worked in a fish pathology lab...

We had to replace our ultra-low freezer (holds steady at -80C), life span of about 5 years, $5000 each. I'm sure they cost more now. We got to know our local heating and cooling repair guy real well as we tried to keep our various incubators and freezers alive as long as possible before we had to replace them. Let alone servicing the building's heating and cooling system.