5 Reasons Your Swamp Cooler Keeps Burning Out

You turned your swamp cooler on a few hours ago, but your house has since gotten really hot. You go to check the cooler and it’s not working. Judging by all the billowing smoke, your swamp cooler must have burned out again. Why does this keep happening?

Here’s why your swamp cooler can keep burning out:

  • The motor’s getting too much voltage
  • The electrical connections have shorted out
  • The shaft bearings can’t spin
  • The fan belt tension is very loose or tight
  • The motor sheave is misadjusted

If this sounds like a lot of information all at once, don’t worry. In this article, we’ll clearly explain why your swamp cooler has burnt out as well as what you can do to fix it. This problem will soon be a thing of the past!

Why Does My Swamp Cooler Burn Out? It Could Be These 5 Reasons!

Excess Voltage to the Motor

The motor within your swamp cooler relies on electricity. Since many evaporative coolers are moderately-sized, they don’t need a whole lot of horsepower to provide cooling to your home. An average voltage range of 115 to 120 volts should suffice.

Compare that to a traditional air conditioner, which requires at least 240 bolts to operate. Yet if you try to run your swamp cooler on that much voltage, you could accidentally damage it. The cooler doesn’t even need to run at 120 volts, but somewhere between 55 to 60 percent of that. It’s just that 120 volts is the evaporative cooler’s max voltage.

Fortunately, you don’t have to guess what the precise voltage capacity of your swamp cooler is. Once you unsheathe the cooler, look at the motor. There on the side, you should see the voltage information printed clear as day.

Voltage bursts are not just bad in that your swamp cooler stops working. The excess voltage can also ruin the circuitry and wiring within your swamp cooler. At that point, you’d have no choice but to buy a new one.

Shorted Electrical Wiring

Speaking of wiring, that’s the next reason your swamp cooler could have burned out. If the wires are all but fried from voltage fluctuations, that could be one reason why your evaporative cooler won’t stay on. Another can be that the connections have gotten too loose, so one of two things is happening.

The wires are either shorting themselves out, giving you limited cooling or the wires have become overheated and thus powered down the swamp cooler. We don’t recommend you get too close to the wires in your swamp cooler, as mishandling wires could lead to electrical shock.

If the wires were incorrectly installed, then contact your swamp cooler manufacturer. You also have to keep the unit maintained to ensure the components stay in good condition.

What if the wires are fine but your swamp cooler won’t stay on for long? It could be an issue with the swamp cooler fuse or the motor itself.

Lack of Oil to the Shaft Bearings

Within the inner workings of your swamp cooler are shaft bearings. They’re also known as squirrel cages in swamp coolers. Shaft bearings may be made of brass or composite materials with a rubber or metal liner.

The swamp cooler motor features two such bearings. The bearings are each connected to an oil port that sends oil into the shaft bearings so they can spin. Another part of maintaining your swamp cooler is double-checking the level of oil in the shaft bearings.

When the bearings begin to run out of oil, they will spin sporadically. If the oil is depleted entirely, the bearings will remain stationary or seize up. This affects the motor, which becomes warm before heating up and turning off.

Belt Tension Set Too High or Low

When you take off the filter pad holder to the side of your evaporative cooler, you’ll see the fan motor. The motor has a belt that runs on a pulley system to keep it moving consistently.

If the swamp cooler belt is old, then it can stretch to the point where it’s too loose to be usable. A worn-down belt will have the same issue. It can’t spin without bumping into other components, which could lead to overheating.

You could try to overcompensate and adjust the belt too tightly. At that point, the pulley system has to work harder to move the belt, so the engine overheats.

How do you know if you have the right amount of belt tension in your swamp cooler? Test it. If you can move the belt about an inch without it being tight or loose, then the tension is set correctly. Do make sure you go back in every few months during the active swamp cooler season to re-check the tension, as it can shift.

Misadjusted Motor Sheave

That brings us to the motor sheave or the part of the pulley system that pulls the swamp cooler belt around and around. A loose sheave will make the swamp cooler’s motor overheat. Then the unit will shut itself off to cool down. When it’s cooled, it will turn back on, but only until it overheats again.

How to Repair an Overheated Swamp Cooler

Now that you have a better idea of what’s caused your swamp cooler to overheat, it’s time to remedy it. If yours is an issue with electrical wires, we again cannot stress enough that it’s best to call a professional electrician instead. You could risk electrical shock injuries or death by handling faulty wiring yourself.

Should you still want to proceed, here are some troubleshooting tips to stop your swamp cooler from overheating.

Lubricate the Shaft Bearings

Dry shaft bearings need attention immediately, but you have to know which brand of shaft bearings you’re working with. Once you have that information, the shaft bearing manufacturer should recommend a specific lubricant.

Use a light hand as you apply the lubricant. Overdoing it is bad in its own way. Now, instead of the shaft bearings being prohibited from spinning, they can spin way too much. The heat the bearings cause from their constant spinning can once again overheat the swamp cooler engine, putting you back at square one.

Set the Belt Tension with an Allen Wrench

If yours is an issue with the swamp cooler belt tension, this is one of the easier and safer fixes.

Take off your swamp cooler’s filter pad holder using a flathead screwdriver. Insert the screwdriver into the end of the filter pad holder and then push from the bottom up until the holder comes off. You’ll next need a crescent wrench as you unscrew the swamp cooler’s sliding motor mount. Make sure you twist the screws counterclockwise.

When you’re done with that, you should be able to access the belt. With a pry bar or an Allen wrench, push the motor onto its side mount. This will add tension to the belt as it’s nearer the fan housing pulley and the fan motor pulley. You may also have to readjust the mounting bolt, tightening it.

Then put the casing of the swamp cooler back on and run it. If you hear the belt screaming or squealing, then you’ll have to go back in and readjust the tension since the belt is too tight.

Fix the Pulleys

If your problem is with the pulleys, that’s another job you can do on your own. Go to your home’s breaker box and power down the breaker switch for the swamp cooler. You may also have to remove the cooler panel from the swamp cooler.

Since you know it’s not a belt issue, make a beeline for the motor bracket. Using a socket wrench, unscrew the bolts but don’t remove them. You need to be able to shift the bracket’s pulley and motor only, so once you can do that, stop unscrewing.

Reset the pulley and motor; a prybar can help if you’re having a hard time doing this by hand. Then tighten all those screws you just loosened, return the casing to your swamp cooler, and it shouldn’t overheat. Oh, but make sure you turn your power back on or the swamp cooler won’t work!

Final Thoughts

Swamp coolers can overheat for a myriad of reasons. Some are electrical, such as voltage issues and bad wiring, while others are due to a misfiring of the internal components. You now have all the information you need to repair your swamp cooler so it runs continuously. Good luck!


Geoff Southworth is the creator of RealEstateInfoGuide.com, the site that helps new homeowners, investors, and homeowners-to-be successfully navigate the complex world of property ownership. Geoff is a real estate investor of 8 years has had experience as a manager of a debt-free, private real estate equity fund, as well as a Registered Nurse in Emergency Trauma and Cardiac Cath Lab Care. As a result, he has developed a unique “people first, business second” approach to real estate.

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