First of all, the main problem people have with evaporative air cooling devices is their ability to produce nice cold air is seriously curtailed when the humidity level increases to high levels. This happens because in order to produce the cooling effect, the air needs to be dry enough to absorb the moisture being added to it by the evaporation process.
When the air becomes saturated (100% humidity) it cannot absorb any more moisture and the cooling stops. At this point, most people give up trying and either return their cherished cooler to the store they bought it from, or they get onto consumer websites and complain with such verbosity that the sky might as well be falling!
Tackling the Problem at its Source
When the "it doesn't work anymore" mindset is activated, there is not much the owner can or will do, so the only solution they see is to replace the low energy cooler with a more expensive (to run) air conditioner. But they are not going at the problem the right way.
The fault is not in the device at all. It is in the climate or environment it is being used in.
A common mistake people make is to treat their swampie like an air conditioner and close all the windows and doors to "keep the cold air in." While that's good practice for AC, it is the kiss of death for an evaporating air cooler.
The reason is pretty simple and you'll kick yourself if you didn't think about this:
As an evaporating cooler operates, it is by its very nature adding moisture to the air in a room. If the room is closed in (all windows, doors and other openings are closed tight), the air in that room becomes more and more humid over time until it reaches 100% saturation point.
At that level, the cooler keeps pumping out a breeze but it stops being cold. The solution is annoyingly simple.
OPEN A WINDOW!
That's right! The simplest way to prevent the air's moisture level in a room being artificially raised to saturation point is to allow fresh air to circulate in from outside.
You can even place the cooling unit in front of the open window so it draws dryer air in from outside and cools it in the room. While it won't make the room as cold as an AC with everything shut tight, it will make it more comfortably cooler than it would be without any temperature control.
The logical thinking here is that by opening a window, you are letting warm air in from outside and wasting the coldness inside. That would be true if you were using AC where you should be doing everything possible to limit the amount of electricity it uses, because it uses a heck of a lot!
Sacrifice a Few Watts
But with a swamp cooler, which uses around 1/20th the energy of AC, it is not so critical to try and conserve every precious degree of coolness by sealing the place up extra tight. You can afford some wastage, which is actually a good thing because it means you can keep enjoying cool air indoors as well as it being freshly cycled from outside.
This is actually much preferable to breathing in stale, recycled indoor air that is very dry and harsh on the lungs (as many AC users will well aware of). Fresh, moist air is good for the respiratory system as well as for a person's health!
The major point here is that you do not need or want to be cold inside your home during summer. You just want to be comfortable and not too hot. A swamp cooler running with an open window will provide enough coolness to make it comfortable and still not cost you any more than a fraction of running an AC.
The Solution is Simple
And there you have the simple, yet wonderfully effective solution. When you run your evaporative cooler by an open window, it keeps cooling you even when the outside humidity rises above 50%, in many cases much higher.
As long as the inside humidity is kept to the same as outside and not allowed to be increased by the evaporation process and no way to cycle with fresh outside air, you can enjoy a cool breeze from your appliance and not get angry with it or feel the need to return it simply because you didn't know how to get it to work just by opening a window!
Annoying, isn't it? But on the other hand, good to know!