Yeah as crazykiddeath said they are rare and are found mainly in cities. But if you do happen to find one do whatever to protect it so the zombies don’t destroy the minifreezers. Just lure them away from it.
As suggested body sites surrounded by unique creatures will have science ids on corpses so that is the safest way to enter the labs. You can also hack the entrance or use a pickaxe/jackhammer to destroy the walls. Yet another way is to cut down a tree and aim it towards the walls though it might require several attempts. Driving your vehicle into the wall might work as well but will require several attempts.
Labs are pretty dangerous so you’d better be prepared. I can’t remember but I think I found a thermometer outside a lab as well or it might have been a barometer. You’d think that there’d be thermometers inside hospitals, doctors’ offices, pharmacies or animal shelters or anyplace medical-related.
On a last note, I have around 9 minifreezers and around 15-20 minifridges but the best place to store food is in an ice lab. Specifically the 2nd floor as its temperature is constant. On the 1st floor (that has the the entrance) the temperature is always -10 degrees colder than the outdoors temperature. In my ice lab the 2nd floor is always -22. Drop your items on the stairs of the 1st floor and drag them down to the 2nd floor. Obviously make sure the area near the stairs on the 2nd floor is cleared first.
