Three of the four sides of the cooler have these grills, which we removed and laid out on top of the wood box to make space on which to work. At the left is the worst of the three grills, covered in a couple of years' worth of hard-water deposits. In the middle is the left-side grill set face down, showing the pad into which the water drips. Air is drawn through the pads and out the front of the cooler by a fan. At right is the rear grill, which was not as badly clogged as the other two.
We went to work on the grills using CLR cleaner, brushes, an old AAA membership card, and a paint scraper. I applied the CLR to the calcified grill sections and scrubbed on it, then scraped using the card. Lisa later got a metal paint scraper and attacked the grill as well. We spent several days chipping away at these grills, mostly in the latter part of the day when the sun was on the other side of the house because doing this work in direct sunlight was pretty unpleasantly hot.
Theoretically, the pads can be cleaned, but we decided that we'd let these get too clogged up and have bought some new pad material from Big R Ranch & Home, which we'll cut to size and throw away the old pads.
After several days of work, we managed to get most of the crud off the grills. I came out one afternoon and was astonished to see how much Lisa was able to remove when she discovered that 3-in-1 oil also acts as a way to loosen the calcium that make it where she could wipe much of it off with a paper towel rather than having to chip it with the scraper.
This looks much better.
I didn't take a picture, but we cleaned the other side of the grills as well, although we did not remove quite as much because you never see the inside part of the grills. However, we did want to clean up the areas where the water pumps into the pads, because that's what provides the cooling; if the feeds are clogged with build-up, the water won't get into the pads, and the pads won't be able to cool things as well.
In the process of scraping the calcification off the grills, we've also taken off some of the paint. We therefore bought a can of the beige paint that most swamp coolers are painted and we'll touch up the paint to reduce rust before reinstalling the grills and pads.
The area where we've been working in front of the house is now covered in bits of loose calcium build-up that we chipped off the cooler, so it's a bit of a mess. I reckon it will stay like that for a while until we get one of the periodic high winds.
This is only part of the clean-up story. The pan where the water sits in the bottom of the cooler was a mess, and as I write this, we're still working on getting it back to a state where it can be used again. I'll have more to say about this soon. Lisa has been doing a lot of work with power tools, while I'm handy to have around when heavy things need lifting. I hope we can get the cooler back together before the worst of the summer heat hits.