Evaporative cooler vs standard AC for greenhouse

[jmforan]

So my 15 year old Champion swamp cooler bit the dust (fan OK but pump motor corroded and lifeless, not to mention corrosion thoughout basin) and I need a replacement cooling device. I have a 13 x 8 foot greenhouse and live in Pasadena,CA climate zone 9B/10A. It is usually dry in the summer but lately (?climate change?) humidity has not bottomed out as often lately. A traditional refrigerant type AC would pull 6 amps, about the same as a replacement swamp cooler, and less expensive to install. I'm able to maintain adequate humidity during dry spells - 35% is the lowest daytime (maybe 10 days during hottest driest summer days) but never below 70% evening and over 70% most of the time. Would a traditional window AC unit be viable or just a rusted wall decoration in 3 years? There are almost no web posts I can find which are trustworthy. Thanks!