In one fast-food restaurant chain (not the one you’re thinking of), there is a surprisingly careless attitude towards equipment. All their machinery is excellent, fit for space travel. It’s always duplicated and can even tell you when it’s not working properly. But the staff in these restaurants completely disregards what the equipment is saying and pushes it to its limits, without even considering calling in specially trained technicians. The ice cream machines die, filled to the brim with ice cream. The conveyor ovens manage to break their chains, and this happens on both duplicated conveyor lines. Refrigerators are no longer used not when they stop cooling, but when, out of desperation and in the absence of oil in the system—which, of course, has leaked out due to a prolonged refrigerant leak—the compressor finally gives out.
Air conditioning units. First of all, there are two of them, and they operate independently of each other. One unit, running at full capacity, is enough to cool the restaurant. Each unit has two compressors. The first one runs continuously, while the second one is on standby. Each unit contains 9 kilograms of refrigerant and can continue to cool even with just one kilogram of refrigerant left inside. I think the engineers of these restaurants planned to comfortably feed soldiers during active combat and direct bombing of the establishment itself.
So, they managed to get to a point where one unit is leaking somewhere and almost all the fluid has spilled out, while in the second unit, one compressor has failed and the second one won’t start. They arrived.
Well, here’s the plan. Let’s keep the first unit running for now. We’ll swap out the compressor for the second one, get it started, and then we’ll deal with the first unit. There’s a lot to do. Keep in mind that everything is on the roof. There’s a vertical ladder leading up to the roof, like a “Swedish wall.” It’s thirty degrees in the shade outside, and on the list of things we need to haul up to the roof are: a suitcase with tools, a nitrogen cylinder, a vacuum pump, a compressor for pumping out refrigerant, cylinders for the evacuated refrigerant, cylinders with fresh refrigerant, an oxy-acetylene torch, the new compressor itself, and some smaller items: a screwdriver, scales, pressure gauges, hoses, and a bucket of water. And we’re in sturdy work pants. We could wear work shorts too, but you can’t kneel down in them often, especially on the scorching roofing felt.
We’re changing the compressor and at the same time checking for a leak in the first unit. While we were changing the compressor, we found that there was almost no refrigerant in the second unit either. Hmm, so there’s another leak. The tank crew got a visit from the fairy. We didn’t find a leak in the first unit up top. When we pushed nitrogen into the second unit, we didn’t find a leak there either. But the nitrogen is disappearing somewhere. While we were looking for the leak, it stopped disappearing. We raised the pressure again — and it’s not going down. Okay, no leak. But, damn, we need to put back together what we took apart while searching for the leak, and we need to return the thermal insulation to the pipes.
In the first installation, we went to look for a leak below. And down there… I don’t know what kind of engineer came up with the idea of mounting the evaporator unit in the attic of the restaurant in such a way that the evaporator rests on a frame structure that obstructs access to the installation itself. Moreover, some of the screws holding the side cover are screwed in from below and are fundamentally inaccessible without winches and jacks.
We somehow managed to reach the internals by bending back the cover where we could unscrew it. We “sniffed” with the detector… strangely, there was nothing. But an oil stain was visible. We searched some more, then searched again, and then… well, I just pressed a napkin to the spot where a leak was most likely, after degreasing it with a special spray, and waited. The leak was found. Very small and in a very unusual place. At the end of the pipe of the collector on the air conditioner’s evaporator. Right in the center of the end. Clearly, it was a micro-crack from the time the unit was manufactured. Refrigerant isn’t leaking because oil accumulates in that spot, and only oil leaks out—hence, it was difficult to find the leak just like that. But how to repair it is unclear. Most likely, we’ll have to remove the entire evaporator and then fix it. And it’s a good thing we had to search for the leak in the upper unit. Getting to the lower one would have been impossible without jacks and a winch.
They didn’t fix it. They prepared a report. Repairing this leak would really take a day or two of work. Let the installation keep running for now. Especially since after fixing the compressor on the second unit, it turned out that it refused to work. Well, of course. The second compressor, the backup one, didn’t want to work either. What happened? A quick call to support. Ah, the control board burned out. Actually, this is quite common—when a compressor dies, it often takes the board with it. But we didn’t have a spare board on hand.
Everything is closed. The state of affairs was recorded in the work order. They came back, essentially, with the same situation they left with. The only difference is that the compressor in the second unit is new, and the location of the leak in the first unit is known. Oh, and they added refrigerant to the first unit to keep it running for a little longer.