These boxes are everywhere around here because certain equipment that needs to be stationed outdoors isn’t happy with the 96 degree F summer outdoor temperatures. They’re an outdoor weather resistant enclosure, with an air conditioning unit attached through one side.

Air conditioning units have two functions. They reduce temperature and humidity. The amount of humidity they remove is proportional to the amount of time the unit is in cooling mode.

This cabinet is very well insulated and has a very low heat load… Watch this Nautel loooooaf along…

Standing next to it, I saw that little a/c pack start maybe once every 10 minutes, for about a minute at a time.

 

Brace yourself, the results ain’t pretty.

 

 

This curious white fungus is attacking rubber parts…

 

 

Various points of moisture or fungus damage…

 

And as an added bonus, open this cabinet on a hot humid day and you’ll be treated to the horrific sight of the equipment becoming soaking wet while still actively running…

 

Insects have been attracted to the cabinet by moisture… This is after a big vacuuming, the junk stuck to the cabinet ain’t gonna yield to that alone…

 

So what’s the solution? I can think of a couple things.

A) do not oversize the air conditioner. This is tricky as heat load is unpredictable and failure to remove enough heat would quickly cause a shutdown or equipment damage.

B) place constantly on LED lights inside to inhibit this mold/fungus growth.

C) use humidity controls on the a/c or a dehumidifier if possible. Not sure if you could easily fit a humidistat to this unit as it’s got its own integrated microprocessor control (hidden behind that piece of filter)… But who knows.