Evaporative Coolers in the West
The hot season is coming and it's time to get the evaporative coolers (swamp coolers) ready for summer. Evaporative coolers function by sucking the hot dry air through filter pads of aspen or plastic mesh that are saturated with water that circulates via a pump in the cooler sump.
They need twice yearly maintenance to even achieve their 5-10 year lifespan. The fan bearings need lubrication. The belts need adjusting or replacement, the circulating pumps need to be cleaned of calcium salt. The dirt and debris needs to be swept and vacuumed from the sump (pan). The pan needs repainting and sealing from rust and inspected to be sure it has not rusted through. The pads need to be inspected and cleaned if they are the plastic fiber blue pads and replaced if they are aspen. The 1/4 " water lines need to be hooked up and inspected for leaks.
Usually the evaporative cooler is on the roof so it's up and down the ladder to perform all of the maintenance and inspections. Frequently there is a sheet metal plate that needs to be removed from the duct under or beside the evaporative cooler and it needs to be stowed for summer to be replaced in the fall. Occasionally the cooler will have a canvas cover that has to be securely stowed.
If the pan has rusted through, it will need to be patched or the whole cooler replaced. I have been successful in having a sheet metal shop make a pan to set the cooler in to extend the life of the cooler, but these days those pans will be too expensive and it's best to replace the cooler. A new 5000-7500 CFM evaporative cooler will run $650-800. If it is on a pitched roof, it can be quite a chore to muscle it up. This is a two person job and you might need a crane.
If you're rehabbing, the best place for the evaportive cooler is on a stand at ground level on the north side of the house. Much easier to maintain at ground level.
Everyone with rental properties in the Southwest knows what I'm describing here. We just replaced two and repaired two on our fourplex. Now all of our residents have nice cool air at the flip of a switch.