10 Reasons Why Your Evaporative Cooler Is Not Working

An evaporative cooler typically stops working because of a damaged (or faulty) fan, pump or blower motor. Electrical issues, water pump problems, inadequate airflow, overheating, and excessive relative humidity can also stop an evaporative cooler from working properly.

Evaporative air coolers are a cost-effective and energy-conserving alternative for air conditioners and many households rely on them for a steady supply of fresh and cool air. However, like all electronic machines, evaporative coolers can become damaged and stop working. 

This article explains how evaporative air coolers work and explains in detail how to diagnosis and troubleshoot the potential reasons why your evaporative air cooler might not be working.  

How Evaporative Coolers Should Work

Unlike refrigerant-based air conditioning systems, swamp coolers operate on the principle of evaporative cooling.  

Evaporation is when a liquid converts into a vapor (or gas), a process that uses heat energy. Heat transfer occurs from surrounding air to water molecules, and is capable of lowering the air temperature by as much as 60°F. 

There are two main types of evaporative coolers and it’s important to know which type of evaporative cooler you have to troubleshoot the cause of your problem:

Direct (Swamp) Evaporative Cooler

A direct evaporative cooler consists of: 

• Fan: draws warm, dry air inside the unit, and its speed determines the rate of cooling 
• Honeycomb Filter or Evaporative Pads: where the heat exchange takes place 
• Water Reservoir: stores water 
• Water Pump: pumps water from the reservoir to the spray water box 
• Fan and Pump Motors: provides the essential mechanical power to the fan and water pump  
• Spray Water Box: sprays water on the corrugated filter or evaporative pads  
• Thermostat: regulates the temperature 
• Blower: propels the cool air into the room 

The water forms a large, hydromel wet film on the evaporative pad (or corrugated honeycomb filter). When the air stream encounters the water film, its temperature drops and is then dispensed into the room as cold and humid air. 

Before turning the cooler on, you can set the temperature level you want in the room. Once the preset level is achieved, the thermostat temporarily stops the evaporative cooling to prevent a further drop in temperature. This ensures a comfortable environment in the room.  

Whole-house, direct evaporative coolers are often installed and connected with a duct system that spreads cool air throughout the house. In contrast, some coolers are placed in an open space and emit heat into the room.  

Indirect Evaporative Cooler

Some evaporative coolers (indirect coolers) do not add humidity to the original air stream. Even though they work on the same principle as the direct evaporative coolers, the water that cools the air is contained in closed tubes.  

When air comes into contact with the tubes, the enclosed water extracts heat from the air. But because of the closed channels, the resultant evaporated water is not added to the now cold air. 

It is important to note that, like water, air also flows in a duct system in indirect evaporative coolers, which is why they are permanently mounted on the floor, windowsill, or roof.  

10 Reasons Why Your Evaporative Cooler Is Not Working

When your cooler starts acting up or stops working, you may notice the following signs: 

• The cooler won’t turn on 
• The blower stops forcing air out of the unit 
• It blows warm air 
• Water leaks from the unit 
• The unit starts making a grinding noise 
• Unpleasant smell from the cooler 

Here’s all the possible causes of a malfunctioning evaporative cooler: 

1. Damaged Motor

If your unit is turned on but is not working, then the most likely cause is damage to the fan, pump, or blower motor (due to impact, short circuit, etc.).

Here’s how to diagnose this issue: 

1. The distinct noise you hear when the cooler is running is because of the water pump. If the noise increases, becomes unusual, or stops, you should suspect a problem with the pump motor. 
2. If the pump motor is fine, but the unit is blowing out warm air, it indicates that the fan motor is not working. 
3. When no air is dispensed out of the cooler it is generally due to a faulty blower motor,

Note that some units use the same motor for all three components; in those cases, the inflow and outflow of air, and the water pump will be impacted together. 

Fix 

You can get a technician to repair the motor. However, broken motors almost always need replacement. 

Since motors are expensive and tend to malfunction repeatedly, it is often better to get a new cooler.

2. Obstruction From Air Pollutants

The air flowing inside the cooler carries contaminants and impurities. While most of the pollutants are dispensed out of the unit with the cold air, some can accumulate inside the cooler, forming clogs or deposits.

These can build up anywhere in the cooler, such as near the fan blades, inside the water sprayer, inlet, outlet, blower, evaporative pads, etc.  

An obstruction near the fan can interfere with its rotation or stop it entirely. This will interrupt the steady inflow of fresh air streams.

Similarly, an obstruction on the blower will prevent air from flowing out of the unit properly. In both situations, you may hear an unusual, loud, grunting noise from the unit.  

If there is a blockage on the spray pores, water will not be added to the evaporator pads or honeycomb filter. Without an adequate water supply, sufficient heat exchange will not take place. 

The disruption in air flow also drives the unit under stress, further disrupting cooling. Overheating may also damage the wiring, causing more complicated or irreversible electrical issues.  

Fix 

Cleaning the unit thoroughly, conducting regular maintenance, and changing the evaporative pads regularly are crucial to resolving and preventing this problem.

If you live in an area with low air quality (AQI), you should consider buying coolers that also have air filters. These filters remove major contaminants from the air before letting them enter the main system.  

How To Clean And Maintain Evaporative Air Coolers

Proper maintenance is crucial to keep evaporative coolers running. Here’s how you should clean a cooler (at least once a month): 

• Turn the evaporative cooler off: Before cleaning the unit, disconnect it from the main power supply and switch it off. 

• Dust The Exterior: Use a clean cloth and wipe the external body of the cooler to remove any dust. 

• Drain The Water: Empty the water tank (remember to look through your user manual for instructions specific to your evaporative cooler)

• Disinfect and Descale: Here’s how to clean the tank:
  • After emptying the tank, rinse it with room temperature water. 
  • Wipe it with a cloth. 
  • Prepare a vinegar solution (1:1 white vinegar and water), and fill half of the tank with it. 
  • Let it sit for 10-20 minutes and then drain. Vinegar disinfects the tank and softens the mineral scales. 
  • You may also use a bleach solution (1 tsp bleach in 1-gallon water) to disinfect. However, make sure your product manual doesn’t advise against it. 
  • After draining the tank, rinse it repeatedly until the vinegar /bleach smell is gone. 

• Brush and Vacuum: Use a soft bristle brush to clean inside the cooler. Use a handheld vacuum to remove dust and debris collected in the pump, spray, or blower.  

• Replace all parts once clean and dried, then plug back in

3. Water Residue

The reservoir on evaporative coolers stores water that is pumped and then sprayed on the pad or honeycomb filter.  

If you use water rich in minerals (hard water) or unfiltered tap water in the reservoir, it may leave behind residues that clog up the pump and make it difficult to force water up to the central system.  

The pump needs additional force to push water, which can then cause the system to overheat. While the water is used up, the minerals and salts are left behind. Over time, they collect and form yellowish scales that breed bacteria, molds, and other germs.  

If you notice unusual noise, frequent overheating, and musty smell from the cold, outflowing air, clogging due to water residues is likely the issue. 

Fix 

Descaling and disinfecting the reservoir and deep cleaning the cooler are critical to fixing this problem.

Using fresh, distilled water in the reservoir can also prevent the issue altogether.  

4. Broken Thermostat

We know the thermostat regulates the cooler and maintains a preset temperature. So if the thermostat breaks down, it will directly impact cooling. 

You can check for a faulty thermostat by switching the temperature settings. If it does not bring about a significant difference in temperature of the air blown out of the system, or you notice short-cycling (even with the fan set to low speed), your thermostat is probably broken. 

Fix 

Get a technician to replace the thermostat (as this is not usually a DIY solution).  

5. Power Supply

Evaporative coolers are electrical devices that must be wired to 120 V AC power (as instructed in user manuals) to operate. Any disruption in the electrical connection directly impacts the machine working.  

If your unit does not turn on, make sure the power cord of the unit is still connected correctly to a working board. 

Fix 

Connect other devices to the power board to check if it’s working. If the outlet is fine, call an electrician to repair the wiring or change the power cord of the cooler.  

6. Water Leakage

Each evaporative cooler has a specific capacity reservoir and, based on that, a particular runtime. If your cooler runs out of water quicker than usual, it may be a case of a water leak. You can confirm it by checking for a water pool around the area where the device is placed/mounted. 

Fix 

A water leak is always caused by cracks in the reservoir of the duct system. Call customer service to seal the leaking areas. 

7. Tripped Circuit Breaker

Whole-house coolers must always have a circuit breaker to protect against short circuits.

Sometimes, the breaker detects a fault and automatically shuts off, cutting the power supply to the appliance. This is called tripping of the breaker, and it is crucial to preventing the cooler from permanent damage. 

Fix 

Turning the breaker back on may solve the issue. Locate the main breaker panel of your home, open its door, and check which breaker has tripped.

Typically, each breaker has a red window visible when it trips. To switch the breaker on, turn the handle to the center of the breaker panel. 

Remember that if your breaker frequently trips, it is essential to fix the original fault in the system before switching on the circuit breaker. Various factors like water around the electrical lines, overloads, double tapping, etc.  

In this case, you must always call a professional electrician to diagnose and troubleshoot the problem. 

8. Inadequate Airflow

If the incoming airflow to the system is disrupted, it will understandably limit any cooling. This issue arises when the system is not placed in an open space, and a wall, furniture, or other objects partially blocks the inlet. 

Other than the reduced flow of cold air, frequent overheating will also indicate this.  

Fix 

An evaporative air cooler should always be placed in an open space, near a window or door.  

9. High Humidity

Humidity factors in when determining the efficiency of an evaporative cooler. Swamp coolers work best in dry areas. When the air is dense with moisture, the evaporation rate naturally decreases; therefore, excessive relative humidity (higher than 60%) can explain why your unit is not working properly. 

While the cooler won’t entirely stop working in these humid conditions, it won’t be able to significantly reduce air temperature.  This is because in humid conditions the air is already fairly saturated with water and cannot hold anymore.

Fix 

Running a dehumidifier with an evaporative cooler can help. Ideally, relative humidity (the ratio of moisture content in a specific amount of air and the maximum water capacity of the said amount) should be between 30 to 50%. 

10. Incorrect Or Damaged Internal Wiring

Your cooler needs a continuous and steady supply of current. Internal electrical issues like burnt, loose (caused by expansion and contraction with frequent overheating), or damaged wiring (due to overload), disrupt the circuit and prevent the unit from turning on or working properly. User manuals often have cable diagrams that you can look through to check the wiring of the cooler. Make sure to turn the power off beforehand to avoid accidents. 

Other than damage, you should also check for incorrect wiring if your cooler has recently been serviced.  

Fix 

Loose cables can be tightened, and incorrect wiring can also be fixed. However, burnt or damaged cables will need replacement. To prevent electrical accidents and to ensure effective repair, we recommend calling the customer service of your cooler’s company.