How to Fix a Swamp Cooler that Spits Water


Summer. We often anticipate it to be the best of times, and yet it can definitely prove to be the worst of times if you don’t like the heat. Most of us have become accustomed to modifying the summer air in our homes, either by air conditioning or a swamp cooler. Whichever method you choose to cool off, when it decides to fail, we can quickly become grumpy and miserable. 

How to fix a swamp cooler that spits water? If your swamp cooler is spitting water out of the front or the sides, chances are you have mineral deposits built-up from your water. To prevent this from happening, thoroughly clean your cooler panels and, if necessary, replace your cooler pads each year before you put your cooler to use.

Evaporative coolers, or swamp coolers,  can be effective in moderate heat. Let’s take a closer look at what works best for keeping your swamp cooler in good working condition.

What to Do If You Swamp Cooler Is Spitting Water

If, after you’ve given your unit a thorough cleaning (and we’ll explain more about this below), you find that it is still spitting water, you can take the following steps:

  • Check the pads
    • Make sure the pads you have in the unit are the right size and have been placed in the unit in the correct position. If the pads are too small or are crooked, water can get past them rather than soaking them as it should. This could result in your unit spitting water.
    • If this is the case, place new pads in your unit, and this should stop the issue.
  • Check the float valve.
    • Just like the float in your toilet, your swamp cooler also has a float valve. Make sure it is set to the right level so that the water is not overflowing. Also, check to see if the tubing is blocked, causing the water to not drain properly.
  • Check your water lines.
    • If the water lines that carry the water into the cooler are loose or cracked, you may end up with leaks or spitting. You can find new tubing at a reputable home repair shop or if you’re not comfortable with performing this type of repair, and HVAC technician should be able to help you.
  • Check your water reservoir.
    • If your water reservoir tray is cracked, you are going to experience leaks from your unit. This is another part you can get from your local home repair store, and your user manual should be sufficient to walk you through the repair. Once again, if the thought of conducting this type of repair gives you the willies, an HVAC expert will be able to help you with this step.

How a Swamp Cooler Works

Swamp coolers use water to cool the outside air temperatures. When it’s working well, an effective swamp cooler can chill the inside air up to 30 degrees from the sweltering outdoor temperatures. These appliances provide cleaner air because it has been purified by the water and filters that provide the cooling process.

When Does a Swamp Cooler Work Best?

Because swamp coolers add water to the air to cool things down, a swamp cooler is most effective in a dry, arid area. Although there are many swamp coolers that are used in the Las Vegas and Phoenix locations, they tend to be most effective when the temperatures don’t exceed 94-95 degrees Fahrenheit.

The unit also works best if the relative humidity in the house doesn’t exceed the amount of humidity being expelled by the swamp cooler.

When Doesn’t It Work Well?

Your evaporative cooler won’t work well in locations that have a high level of outdoor humidity. If there’s too much moisture in the air, the cooler’s pads won’t be able to absorb much, if any, additional water making it impossible for it to work effectively.

If the temperatures are too high, your swamp cooler will have to work much harder and most likely won’t be able to get enough water to the cooling pads. To counter this, you will want to increase the amount of water flow to your swamp cooler pads by about 50%. This will keep the unit’s pads from drying out and will help it effectively cool your house.

Maintaining Your Swamp Cooler

As with most things around your house, a little preventative maintenance will go a long way when it comes to your swamp cooler’s operation. Before starting your cooler in the spring or summer, take time to do the following:

  1. Clean the swamp cooler panels.
    • Once you’ve taken the cooler panels out of the unit, thoroughly scrub them with a stiff brush and a solution of 1 cup of white vinegar to 1 gallon of water. Make sure you remove all mineral build-up and rust from the unit.
    • Note: If you had rust that you needed to remove, repaint those areas with an appropriate appliance paint as indicated by your user manual.
  2. Check your cooler pads.
    • Because these cooler pads are such an integral part of making your swamp cooler work in an effective manner, you will most likely want to replace them two to three times per season of usage.
    • Pro Tip: Wait to change your cooler pads until you do your pre-season cleaning, so you know they are clean and haven’t been sitting around gathering debris during the winter.
  3. Know your water.
    • Your swamp cooler uses water instead of freon to make the cool air. If you live in an area with hard water, you will want to clean your unit every two or three weeks to prevent mineral build-up that can cause your unit to spit water when it shouldn’t.
    • Pro Tip: Do NOT use softened water. The salt used in water softener units will cause faster mineral deposit build-up inside your cooler.  I’ve had good luck using an inline calcium inhibitor filter for mine like this one on Amazon.
  4. Drain your unit.
    • At the end of the season, before you cover your cooler for the winter, make sure you drain the water out of your unit. 
    • Provide it with another good scrubbing with your vinegar mixture. And it’s also a good idea to run it in the fan-only mode for about an hour after draining and washing it. This will help everything dry and prevent mold from growing while it is at rest.
    • Pro Tip: Use a canvas tarp to cover your evaporative cooler in the off-season. This will not only help protect your unit but will also deter cool/cold air from entering your home when you don’t want it.
    • For more tips our How To Clean a Swamp Cooler

Benefits of Using a Swamp Cooler

Many people in dry climates prefer swamp coolers over refrigerated coolers because they are:

  1. Less expensive to operate – sometimes by up to 50% less over traditional air conditioning units.
  2. More eco-friendly – evaporative coolers leave a low carbon footprint because they do not produce emissions. Neither do they release toxic chemicals into the air. They do use electricity to operate, but so do their refrigerated counterparts.
  3. Often portable and practical – apartment and RV dwellers often have small swamp cooling units in their living area because it is more practical for the available space.
  4. Adds humidity to the air – too much dry air can be hard on your lungs, throat, and nasal passages. An evaporative cooler adds small amounts of much-needed humidity to your living space’s air to provide you with better breathing health.

In Conclusion

Now you know how to maintain and, in some instances, repair your evaporative cooler. Your unit need not be rude any longer and should stop spitting water at you and your guests. Enjoy your cool air.

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