Revive Your Rusty Evaporative Swamp Cooler Peeling or flaking doesn't mean it's time to replace

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Filling the clean, rustless water pan with water

With a couple of hours and about $100 in materials, our 20 year old evaporative (swamp) cooler is good as new. Now it should last another 20 years and yours can too!

The Problem  

Time and exposure to harsh weather take a toll on evaporative coolers. Our swamp cooler water pan had paint that had peeled and flaked, resulting in rust. A leaking swamp cooler can create costly water damage, so something had to be done. 

Was it time to replace the evaporative cooler, at a cost of well over $1,000? Could the rusty swamp cooler pan be revived and saved from its watery woes? 

Rust, corrosion, flaking paint, frayed fan belt…

Rust, corrosion, paint flaking, fraying fan belt

Evaporative coolers, commonly known as ‘swamp’ coolers, are fantastic, energy efficient cooling solutions, but over time, their metal pans can succumb to rust. 

The Solution:

Watch the video to see in much greater detail, how to transform your rusty evaporative swamp cooler water pan. Don’t replace it – revive it!

This DIY guide will show you how. With just a few hours of work, patience for drying time, and around $100 in materials, you can save serious money and make your cooler pan work like new!


Start by cleaning the pan and removing peeling paint and rust. A pressure washer or a high-pressure hose nozzle can help. 

Use a hand scraper, oscillating multitool, sandpaper, or a wire brush for tough spots. You don’t need to remove all the rust, just the loose bits. Give it thorough cleaning after this step to make sure any oil or debris is removed so the paint will adhere properly.

I’m using the HOTO Tools 20V Cordless Pressure Washer to clean my evaporative cooler. Check out my review to see it in action.

Apply Paint

Use a quality interior/exterior spray paint to touch up rusty spots inside the cooler. Use enough coats for moisture protection, which was three coats for me. Focus on corners and areas near the water line. You don’t need to paint the entire interior, only areas needing protection. Paint the inside of any corroded side panels, and the wire frames.

For the exterior, use color-matched exterior paint or go for a new color. I gave each exterior panel and the body of the swamp cooler several light coats since the sun had caused the paint to fade and become chalky.

Apply Patch & Seal Tape

I recommend Gorilla 4-inch by 10-foot white Patch & Seal Tape. Apply it to a clean, dry pan, overlapping by about an inch. Ensure it extends past the water line. Be cautious and take your time; the tape is sticky and can’t be repositioned.

Peel the tape liner partially, then unpeel it as you apply it. Press down firmly, especially at overlaps. Fill gaps with patches. The tape conforms to the pan’s curves.

Apply Rubberized Coating

You might find a coating specifically designed for evaporative coolers in hardware stores, but most are asphalt-based, and I had concerns about potential toxicity. Flex Seal specifies that their coating is non-toxic after a full cure, making it my choice for the rubberized coating.

I used clear Flex Seal because I had some leftover from a previous project. However, I suggest going with white to make it easier to see how thoroughly it’s being applied to ensure no spots are missed. To avoid a messy cleanup, disposable brushes are a good idea.

Allow the first coat to dry for the recommended 24 hours before applying a second coat. I used a bit less than half of a 32 oz can, and your mileage may vary, but it’s handy to have some extra around the house.

Let the coating dry for the recommended 48 hours before filling the pan with fresh water. The white surface of the pan makes it easy to spot any dirt or debris accumulating in the water.

Additional Tune-Ups

Since I was already on the roof, I took the opportunity to perform some additional maintenance. Clean the blower wheel thoroughly to remove any dirt that may have hardened on the blades due to the moist air. A bottle brush and a shop vac can help with this task.


Replace any fraying V-belts and oil the blower wheel bearings.


Consider switching to Aspen cooler pads, which are thinner but can significantly improve cooling efficiency. They may need to be replaced each season, but at $5 each, the added cooling is worth it.



And there you have it! Your evaporative cooler pan has gone from rusty to refreshed in just a few simple steps. So why spend a fortune when you can stay cool without breaking the bank?

Thanks for joining me on this “cool” journey at Uncharted DIY. If you found this article helpful, please leave a comment so we can share our knowledge with even more DIY enthusiasts like you. 

Disclosure: Some of the links below are affiliate links. At no extra cost to you, I may earn a small commission on items bought using them. These are the same recommendations I would make regardless of any compensation. For products that I have older versions of, I recommend the items that I would replace them with if I were buying them new. 

Flex Seal Liquid 32 oz Rubber Coating in White

From Amazon

Dial Manufacturing Cooler Spray Paint for Outside of  the Cooler

From Amazon

Probably less expensive locally, if you can find it

RMotor / Fan V-Belt (Drive Belt)

From Amazon

This fit my cooler, but measure your old belt for correct size

Aspen Cooler Pads of the correct size to fit your cooler

These are stupidly expensive online – 5 to 8 times more – probably due to difficult shipping. I won’t even link them here! Instead, try your local hardware store, where they should be under $10 each


There are more DIY projects in the works, so stay tuned to Uncharted DIY. Feel free to comment, post photos, or ask questions.

Uncharted DIY is for DIY enthusiasts tackling uncommon projects, utilizing common tools and often on a limited budget

Uncharted DIY is for DIY enthusiasts tackling uncommon projects, utilizing common tools and often on a limited budget