Swamp coolers, also known as evaporative coolers, cool homes in low humidity regions. The process is simple. Water is cycled through the cooler and then pushed out into the home. Since the water recycles through the unit, it tends to create deposits, corrosion and odors over the course of the hot season. The problem worsens and can affect performance if you do not do proper maintenance between seasons.
Drain and clean the swamp cooler following manufacturer's instructions. This is necessary to remove any debris, mold, mildew or deposits that may be causing the odor. You may need a brush to remove deposits and to clean the side panels. Check the pads as well and clean or replace if needed. Use simple soap and water to give the evaporative cooler a thorough cleaning. Sediment build-up in the panels, pad, in the base or motor can impede water flow. This may create an environment ripe for mold and mildew.
Add a cup of vinegar to the cooler pan and let the vinegar cycle through the system for up to an hour. This will eliminate odors, mold, mildew and some corrosion, calcium deposits and other types of build-up. Repeat one to two times a season or as needed.
If the vinegar odor bothers you, drain the cooler once more. Once clear water has cycled through for a while, the vinegar smell will disappear.
As with most things, prevention saves you a lot of headaches. As part of your winterizing maintenance, use the vinegar deodorizer and drain the water from the swamp cooler. Water left to sit for a prolonged time leads to stale odors, mold, and deposits. Don't forget to remove the pads. If the pads are left in the cooler, they may stick to the panels and build up odor over the winter. If you plan to use the pads again next year, they too can be sprayed with a vinegar solution and rinsed prior to storage.
Avoid using bleach or other harsh cleaners that may damage the swamp cooler unit or cause respiratory problems for your family.