Not that simple. For marine
installations, some systems are designed for DIY and you screw them together, with seals on the joints. That's still seals that can leak. And if you are engine-powered, you won't have a sealed metal bubble around the compressor, as home AC-powered units do. So your mileage can vary.
But automotive AC systems DO NOT regularly need gas topped up every three years. They may typically have 2-3# of refrigerant in them, and leak detectors can pick up a loss equal to 1/4 ounce per year, in the right trained hands. You can find and fix a leak way before it would "need" a top-up. Not to mention, the average car in the US now is 11 years old, and most of them have never needed AC service
. Ten years or longer is not unusual. "Topping up" a leaked system, in any amount, without trying to find and fix the leak, would be a licensing violation.
The rotary compressors are sealed by a graphite shaft seal
, compressing a saturated (by the oil) felt disc against a stainless steel
seat. Eventually the graphite wears out, or a spec of dirt cuts the seal, or the felt wears out. But ten years is not uncommon with no appreciable loss, as long as that felt is kept saturated with clean oil
An ice box never has these esoteric problems.(G)