Swamp Cooler not Blowing Cold Air (8 Fixes)

Your swamp cooler is not blowing cold air? In this article, I guide you through fixing your swamp cooler.

To do that, we’re going to check the different possible reasons why your swamp cooler is not blowing cold air. For each cause, I list a way to test for this cause and one or more methods to fix it.

Quick answer: A swamp cooler is not blowing cold air when the fan does not blow air or when the water pads are not soaked. Possible causes include a broken fan, clogged air filters, a broken water pump, or clogged water lines. Usually, cleaning the clogged parts, replacing air filters, and checking the connection points of the water lines solves the issue.

But there can be many more reasons and possible fixes!

Don’t worry, we’re going to check almost every possible swamp cooler problem in this article!

Let’s first have a look at a rough overview of all the issues causes in this article:

Summary: Reasons for a swamp cooler not blowing cold air

ReasonHow to fix it
Broken fanReplace the fan
Clogged fan or air filterClean the fan and replace air filters
Dry water padsRefill the water pads manually
Water pump brokenReplace water pump and connect water lines tightly
Water level sensor brokenReplace the water level sensor
Clogged water linesClean water lines with a wire brush and vinegar or lemon juice
Thermostat brokenReplace blown or broken electronic parts
Ripped or worn-out V-beltReplace the V-belt with a matching-size one
OtherGet a new swamp cooler

8 Ways to fix your Swamp Cooler not blowing cold air

Let’s have a look at all the different reasons for your swamp cooler not working, and ways to test and fix it!

1. Fan broken

One of the most common reasons for a swamp cooler not blowing cold air is when the fan stops working.

Swamp coolers are evaporative coolers. So, by definition, they only blow cold air when water evaporates.

Without a constant airflow, the water in the soaked water pads won’t evaporate quickly. Technically, there is still evaporation. It’s just much less than with a working fan.

Slow evaporation does not produce noticeable cold air, because before the cold air from the evaporation process reaches you (which takes a while because there is no airflow), it heats up.

So, an evaporative cooler with a broken fan is a humidifier at most.

But why do swamp cooler fans break?

When you compare the fan inside an evaporative cooler with a regular pedestal or floor fan, one difference is apparent. Swamp cooler fans can’t move as freely as other fans.

They have to press air through soaked water pads. This increases the wear-down rate of swamp cooler fans.

The bearings, fan blades, and rotational axis have to exert and withstand much larger forces than regular fans.

You can verify this with a simple experiment. Try to blow air through a sponge. Then blow air without any obstructions. The difference in blowing power needed is significant.

The fans inside swamp coolers unfortunately rarely are any better than regular fans. Especially in portable swamp coolers.

It makes me wonder why manufacturers put these regular fans inside swamp coolers. But well… it’s all about the money.

swamp cooler broken fan part
A broken plastic part blocking the fan in a swamp cooler can cause it to stop working

How to test

Testing a broken fan is very simple. Just turn on your evaporative cooler and see what happens.

Does the fan blow air? If yes, then your fan works… obviously.

If your fan does not rotate then it is likely broken.

Now, you have to find out why it does not rotate. First off, are there any obstructions in the fan blades?

If there are obstructions, then head over to the next section which is about clogged fans.

If, however, your fan does not rotate at all, even though it is free of dirt, dust, and other obstructions, these could be the reasons:

  • Broken or corroded fan power supply
  • Thermostat does not activate fan
  • Broken bearings

You can do the following quick test:

Disconnect the fan and connect the wires to a battery. Does it rotate now? If yes, then your fan is working fine and the problem is somewhere in the electronics of your swamp cooler.

However, if it does not work, then your fan is, indeed broken.

You can oftentimes hear an accompanying buzzing noise coming from your swamp cooler’s electronics.

That’s because the swamp cooler receives electric power from the power supply, but, because the fan does not blow, the swamp cooler can’t use the power anywhere.

Power always needs an outlet. Oftentimes, it ends up in the electronic circuitry where it overloads capacitors and inductors, or the electromagnetic motor inside the fan, which starts buzzing.

How to fix

If your fan is broken, you have to replace it with an equivalent replacement part. Fan sizes vary with the swamp cooler’s size.

So, there’s no one-fits-all solution.

Small indoor portable swamp coolers should be compatible with this Noctua fan (click here to view it on amazon).

Please note that this is actually a computer fan. So, it is only for small evaporative coolers.

For larger swamp coolers, it’s difficult to find a model that fits all.

To find a proper replacement, open your swamp cooler, find the fan model number and look for replacement parts online.

If you can’t find a proper replacement fan, then you can measure the fan’s dimensions and find a replacement fan that roughly matches.

And if you still can’t find anything that fits (some swamp coolers have very uniquely-sized fans), then you can also just get a new swamp cooler.

( I recommend a quality model that won’t break at the bottom of this article )

2. Clogged fan or air filter

Another possible cause for your swamp cooler not blowing cold air is a clogged fan.

A clogged fan is much better than a broken fan because it’s very easy to fix. You just have to do a thorough cleaning.

Swamp coolers rely on constant airflow to work. However, the air in our living spaces is full of dust. So, essentially, swamp coolers are drawing a constant stream of dust.

The air draft always passes through the soaked water pads. The water pads filter the air.

So, there are two or three places where dirt can build up:

  • The fan itself
  • Water pads
  • The air filter (if one is present)

Not all swamp coolers have air filters, so the last point is optional.

With increasing running time, the amount of dust, dirt, and grease inside your swamp cooler increases.

Each increment of dust inside your swamp cooler reduces the airflow.

So, it is mathematically just a matter of time until your swamp cooler stops working due to full dust blockage.

air filters dirty clogged
Extremely dirty air filters prevent proper airflow and therefore stop your evaporative cooler from cooling (image by DanDaue)

How to test

To test for this cause, open your swamp cooler and check the fan, the air filter (if there is one), and the water pads.

If your swamp cooler is clogged, you should see a lot of dust or dirt inside it.

How to fix

First of all, remove the water pads from your swamp cooler. Rinse them in running water. You can also add soap to get the grease and bacteria off. You will see a lot of dirt coming out.

Then you can place the wet water pads in your swamp cooler again. They need to be wet anyways, so there’s no real need for drying at this point.

Then, clean the fan using a dry brush. You can just use an old toothbrush for this.

If there is sticky grease on your fan, you can use a fat-dissolving kitchen grease cleaner.

However, if the clogging is merely due to dust, use the dry toothbrush without additional cleaning products.

Liquids and dust usually don’t go well with each other. Either the dust gets more dense, or it starts growing mold and stinks.

You can unclog your air filters with a dry brush as well. However, you should replace the air filters regularly anyways.

So, use this as an opportunity to put in new filters! New filters will allow for much better airflow.

3. Dry water pads

Another possible cause of your swamp cooler not blowing cold air is when your water pads are dry.

Evaporative coolers need water to work. The water in your swamp cooler’s water pads absorbs the heat energy from your living space to vaporize.

This leaves cold air behind, which the fan in your swamp cooler then blows into your room.

If your swamp cooler’s water pads are dry, it is basically just a fan.

Now, you might wonder why I even list dry water pads as a point. In the end, it’s the most obvious reason for a swamp cooler not cooling.

The reason is that dry water pads are usually a symptom of other issues in your swamp cooler.

In the next sections, we dissect these deeper causes.

So, let’s first check the state of your water pads.

How to test

Open your swamp cooler and touch the water pads. Do they feel wet or dry?

Alternatively, you can remove the water pads and squeeze them out over your kitchen sink. See how much water comes out.

How to fix

To fix dry water pads, you have to first find out why they are dry. There are multiple possible reasons for dry water pads.

The most common causes are a broken pump, a broken water level sensor, or clogged water lines.

Also, if you refill your swamp cooler manually, then forgetting to refill can also be a cause.

Let’s have a look at each of those issues in the next sections.

4. Water pump broken

When the water pump in your swamp cooler is broken, it can’t refill the water pads.

So, after some time of running your swamp cooler, after all the water in the water pads evaporates, it stops blowing cold air.

Broken pumps are very common. And they are hard to detect since the blowing fan in a swamp cooler produces the illusion that your swamp cooler works fine.

How to test

Turn on your swamp cooler (with dry water pads) and listen for pump sounds. If your pump works, it should switch on soon.

There are two possibilities now:

Either your pump turns on and makes the typical pumping noise. Or it doesn’t turn in.

If it doesn’t turn on, you can assume it’s broken.

However, if your pump turns on and the water pads still don’t refill, the issue might be in the water distribution lines connected to the hose.

Maybe there is a loose connection.

How to fix

If you absolutely hate fixing electronics and replacing parts, you can technically refill the water pads manually.

But it gets annoying after some time. So, I recommend fixing the issue instead.

You can replace most swamp cooler pumps with this Dial Manufacturing UL standard pump (click here to view it on amazon).

If you suspect your pump still works (because it makes a noise), then double-check all the connection points of the water lines.

See, if water leaks anywhere. You can follow the path of water coming out of the pump. At one point you should see a leak.

If you don’t find anything, it might be the case that your pump is broken, but still makes a noise. This can happen if the bearings inside are worn down, or when an internal part is clogged.

5. Water level sensor broken

Some swamp coolers have a built-in water level sensor. The water level sensor either measures the humidity of the water pads directly or the water level of an internal water tank.

The water level sensor signals the electronic control system whether the pump needs to turn on and refill water, or not.

When the water level sensor inside your swamp cooler is broken, the pump won’t turn on.

And, therefore, your swamp cooler soon stops blowing cold air.

How to test

Check whether your swamp cooler has a built-in water level sensor.

You can either do that by checking the manual. Or you simply open up the swamp cooler and see if there is any sensor-like device that’s mounted to a water tank or to water pads.

Now, technically, if the water level sensor is broken, you can’t really test it directly.

But you can imitate a working water level sensor by applying a small voltage to the connection points of the water level sensor.

You should only do that if you are familiar with electronics.

You can apply such a small imitation voltage to the circuitry using a battery or a voltage generator.

How to fix

Fixing a broken water level sensor is usually simpler than testing it.

Just find the part number of your water level sensor and contact the manufacturer for a replacement part.

Maybe you can also find a matching part online. Replace the water level sensor.

After replacing, when you run your swamp cooler again, the sensor should signal the pump to turn on and refill the water pads again.

6. Clogged water lines

Swamp coolers have two water-carrying components:

One water line connects to the swamp cooler from the outside. This is usually the water line connecting a tap or a tank of water with the swamp cooler.

And then you got the inside part of your swamp cooler. There, the water line splits up into multiple individual lines (depending on the specific swamp cooler model) which refill the water pads.

If the water line is clogged, it can’t distribute water.

Normally, water lines don’t clog. However, depending on the water source you use, algae, lime, and dirt can accumulate in the water lines over time.

swamp cooler water line
When the water line in a swamp cooler is clogged, too little water flows through it and your water pads don’t get humid enough to produce cold air

How to test

Disconnect the water lines from your swamp cooler. Try to pass water through them and see how well it flows.

Some water lines are transparent, so you might even be able to see obstructions.

If you notice the water does not flow properly through the hose, then it is likely clogged.

How to fix

Pass a wire brush through the water line and unclog it. Most water-induced clogs are easy to unblock.

However, sometimes, especially with limescale, it is hard to remove with a brush.

In this case, you should first dissolve the limescale with vinegar or lemon juice.

Alternatively, just get a new water line. Usually, they are just a few bucks at hardware stores.

7. Thermostat broken

Thermostats control other components, the so-called actors, in your swamp cooler, such as the water pump and the fan.

The thermostat is the brain of your swamp cooler. It knows your current room temperature and the wetness of the water pads. And based on these two inputs, it controls the pump and the fan.

When the thermostat inside your swamp cooler is broken, your pump and fan either won’t turn on, or they will turn on unexpectedly.

For example, a well-working thermostat won’t activate the fan when the water pads are dry. First, it refills the water pads. And only then it turns on the fan.

But running the fans with dry water pads does not make sense.

A broken thermostat can cause these kinds of pointless behaviors, which can cause your swamp cooler to not blow cold air.

How to test

The thermostat is the mediator between many different components in your swamp cooler. So, it is very hard to troubleshoot.

The best way to verify that your thermostat is broken is by activating the pump and the fan manually.

You can only do that if you have a third-party power source such as a voltage generator.

When the pump and fan work when you power them manually, but not when the swamp cooler runs, then your thermostat is broken.

How to fix

You can’t really fix a broken thermostat in most cases. Usually, thermostats vary significantly between manufacturers. So, there is no one-size-fits-all thermostat that you can put in any device.

If your thermostat is broken, I recommend getting a new swamp cooler.

Usually, thermostat repairs are not worth the time and effort.

If, however, you are dedicated to repairing your swamp cooler’s thermostat, the first thing you should look at is the thermostat’s circuit board.

Look out for blown or broken parts. Usually, when there is an electronic issue, you can see it.

Then, check the connection points between the actors (pump, fan), the thermostat, and its sensors (water level, thermometer).

If you find an issue in any of those places, you can usually fix it yourself with a replacement part and a soldering iron.

However, if you don’t find the issue, then the problem might be a hard-to-detect water damage.

8. Ripped V-belt

In large swamp coolers, the motor and fan are separate components. They connect with a V-belt.

Not all swamp coolers have a V-belt. Smaller coolers usually power the fan directly. But large swamp coolers such as roof units have a separate motor and fan.

When the motor axis rotates, the V-shaped belt transmits the rotational movement to the fan.

So, the point of the V-belt in a swamp cooler is to connect the motor and fan.

And when a V-belt breaks, it, obviously, can’t transmit the rotational power to turn the fan. And then, your swamp cooler stops blowing cold air.

Usually, V-belts last a very long time. They are even used in cars. And you rarely have to exchange them.

However, because they are moving parts, they wear down with time. And so it can happen that they tear.

ripped v-belt

How to test

Open your swamp cooler and check the V-belt. You can immediately recognize a torn belt.

But it might also be the case that your V-belt is not entirely torn but very worn out.

In this case, turn on your swamp cooler and see whether the V-belt is able to power the fan.

A worn-out V-belt slips and doesn’t transmit rotational power.

How to fix

Check the dimensions (width and length) of your evaporative cooler V-belt. Then, get a matching replacement belt.

I recommend this replacement V-belt (click to view it on amazon). You can pick different size options. Get the one that fits.

To find a matching width and length, either measure the torn V-belt in your evaporative cooler. Or read the specs on the label imprinted on the belt.

V-belts like this are used in large swamp coolers

What if your swamp cooler still is not blowing cold air?

Most swamp cooler problems are relatively easy to fix. However, if you can’t find or fix the issue in your swamp cooler, then I recommend getting a new one.

I recommend this Hessaire evaporative cooler (click here to view it on amazon).

This one is a bit more expensive than other portable evaporative coolers. But I always prefer to get a quality product once than to have to rebuy things.

Getting a new cooler not only solves your cooling problem but it also saves you hours of troubleshooting and fixing time. And maybe even a technician to inspect it.

So, it’s money spent to worry less.

That’s a great philosophy to live by and a good use of money. Instead of wasting money on your broken device, buy yourself the stress relief and get a working quality product.

You can sell the broken device online if you like. Lots of people like to repair things and happily buy defective devices. Another win-win situation.

You get rid of your old, broken stuff, and you make someone else happy.


Most swamp cooler issues boil down to the fan not rotating or water supply issues.

To fix your swamp cooler, make sure that the water pump works, the water lines are unclogged, and the fan rotates.

Using the causes and fixes in this guide, you should be able to fix 95% of swamp cooler issues.

However, if you can’t fix your swamp cooler and you are sick of researching possible issues, just get a new device.

You don’t gain anything from driving yourself to despair!