coolingevaporative-coolinghvac
I know these pads are at least 4 summers old, but not sure how old exactly. As I was shutting the swamp cooler down for the winter, I saw that they seemed really dirty. The white material flakes of really easy.
I don't know if I need to clean them or actually replace them?
That's just scale and mineral buildup. Evaporative coolers work by evaporating water; when they evaporate hard water that has minerals in it, the minerals stay behind. The better coolers have constant bleed lines or purge pumps to prevent this buildup by flushing it away. You can do it yourself by periodically draining all the water in the sump. Or you can install a bleed line or purge pump yourself.
But if you have one of the old coolers that uses thin aspen pads, know that you have to replace those pads at least every year. That type of older cooler requires a decent amount of maintenance; if you're not willing or able to do it, I would recommend replacing it with a newer unit that uses thick rigid media that lasts a long time instead of those aspen pads, and has a bleed line or purge pump to keep the scale buildup down.
At minimum, you should drill weep holes in the cans to allow standing water to drain. If you are ambitious, remove them. The globs of tar you see at the lower edges were used to waterproof the fasteners that attach it to the roof. Scrape off the tar and remove the fasteners. Patch the fastener holes with roof tar. Remove the entire flashing, tuck the up-slope edge of the flashing under a course of asphalt shingle, apply roof tar under the flashing at the fastener hole locations. Fasten down then tar over the fastener heads again.
A manufactured version of the same style of mount is pictured below, note the weep hole.
Best Answer
From the looks of those wet water filter pads I do not think I would want air sucked through them to be circulated around my house.
Get some clean new ones. They are not really that expensive.