When we were told that the refrigerator at the zoo had broken down, and not just any refrigerator but a freezer, the first thing that came to my mind was the display with the penguins. However, the reality turned out to be much more mundane and dramatic. The mundanity was that it was a refrigerator for food, specifically for fish. The drama lay in the fact that, as it turned out, there are far more dead animals in the zoo than living ones. And it’s unclear whose life and death is more preferable—the fluffy white rabbit that has become a carcass in a block, or the deceased mouse that was free but never buried, now dried up on the rarely visited concrete steps of the technical areas.
What broke? They say it’s the differential. Oh, wonderful. If things are bad, you can spend a whole day searching for the issue and still not find it. We arrived, found the control panel, located the compressors, and figured out which one was from the broken freezer. We opened the panel, and there it was—on the main three-phase switch, the very wire responsible for the ground had burned and melted, damaging the switch as well. Ha, problem solved, issue closed. We’ll install a new switch later, but for now, let’s quickly connect the ground through the terminal block.
But the thought that such a current was flowing through the “ground” that it melted the terminals just wouldn’t leave me. And it’s true — we turn it on — it doesn’t work. Well, let’s start looking for the problem. We have the tools, so we go from point to point in order. We figure out where and how the cables are running. We’re freezing in the still cold freezers. In one of them, there are dead chicks and rabbits — just like that, with their skins on. In another one, which was the first to break down, there are various types of fish, by the way, for those very penguins. We open the control panels of the evaporators, measure — nothing!
After 4 hours of searching, running around with a heavy extension cord that feels like a ton because it’s meant for a welding machine and has a really thick cable, we finally found the door switch for the freezer. This switch turns off the fans on the evaporators—so that a person entering the freezer doesn’t freeze to death faster than they expect. Inside the switch, we found a lot of water. That was causing the short circuit. We removed the water, sealed it with silicone, and went to turn it on… It doesn’t work. Well, it works, but not quite right. The compressor turns on when you switch off the breaker for another compressor.
After another half hour of troubleshooting, it turned out that when the ancestors assembled the unit, they installed two compressors on one freezer that were supposed to work alternately. One of the compressors turned off according to a timer relay, while the second one kicked in when the first one started working. Apparently, the relay died when there were issues with the first compressor shutting off by differential, which caused a glitch in their operating sequence.
The glitch was fixed by shorting the timer relay and promising to return with a new relay, along with the main switch that had melted. But now the penguins can sleep peacefully. And dream. And turn green in the spring.