Why Is My Dehumidifier Blowing Cold Air?

A dehumidifier is a valuable investment for those who live in humid regions. You may suffer from hot summers made worse by the humidity, or cold and wet winters when you just can’t seem to get comfortable. A good dehumidifier is your best solution to high humidity. But your responsibility doesn’t stop at just buying the best dehumidifier. Keeping your dehumidifier working properly through different seasons will also require your time and effort. However, since it’s still only a machine, you might still encounter some problems.

If you notice your dehumidifier blows cold air, the simplest answer is because of cold ambient air. But if this isn’t the case, there can be other causes you may find such as a clogged filter or dirty coils. We’ll talk about these possible causes and give you some tips you can do to solve the problem. In any case, it’s always best to consult your manual. If the problem seems severe, ask your manufacturer or contact a licensed technician to check your dehumidifier.

How Does a Dehumidifier Work?

First, you must understand how your dehumidifier works so you can tell when it’s not working properly. Dehumidifiers extract moisture from the air using different methods. What most people are familiar with is the compressor or refrigerant dehumidifier. Dehumidifiers work similarly to an air conditioner that uses a compressor to pump the refrigerant to the coils. 

A fan draws the humid air in and the air passes over the cold coils. As the warm air cools down, it loses hold of the moisture. Water is collected in the tank or it flows out through the drain hose. Meanwhile, the air is then reheated and exhausted into the room. This type of dehumidifier generally performs well in warm and humid conditions. Its efficiency starts to decrease as it gets colder and will stop operating at 41°F. Since it relies on condensation, the condensate may end up freezing on the coils instead.

The other main type of dehumidifier is called a desiccant dehumidifier. It uses a hygroscopic substance to extract moisture from the air by absorption or adsorption. Full-sized residential units typically use silica gel filled into a rotating wheel. After pulling moisture from the air, the silica gel is heated to remove the moisture. Since this type of dehumidifier heats up the air before condensation, there are fewer risks of freezing. Thus, it can work in lower temperatures, usually down to 33°F.

How Does a Dehumidifier Work

Why Does a Dehumidifier Blow Cold Air?

Before you can find the right solution, it’s crucial to know exactly what’s causing your dehumidifier to blow cold air. Once you have pointed out the root cause of the problem, you’ll know what to do to prevent it from happening again.

Low Temperature

As mentioned, dehumidifiers generally work best in warmer conditions. Low temperatures do not go with refrigerant dehumidifiers in particular. If your dehumidifier is blowing cool air, it may simply be because the ambient air is already cold. Even with desiccant dehumidifiers that can operate in lower temperatures, if the intake air is cold, the air it exhausts would also be cold. When the temperature drops below 60°F, refrigerant dehumidifiers require greater power to cool the air down for condensation. Thus, the air may feel even colder. If temperatures drop even further, the condensate may freeze up. When this happens, the unit needs to defrost.

Low Temperature

Auto Defrost is Activated

When the frost is detected on the coils, your refrigerant dehumidifier will go on auto defrost. In defrost mode, the unit stops dehumidifying while the fan continues running to melt any ice buildup. If the airflow isn’t blocked, this should melt the ice and allow the unit to resume operation. While defrosting, the unit may produce cold air due to the ice melting inside.

Clogged Air Filter

Before the air enters your dehumidifier, it passes through the filter(s) to remove any impurities and protect the internal components of your dehumidifier. Over time, the air filter can get clogged with dust, dirt, and other particles, limiting the airflow. Without adequate airflow, the fan will not be able to melt the ice when defrosting, resulting in frozen coils, and thus, cold air blowing from your dehumidifier. Dirt on the coils due to clogged filters can also affect its cooling performance, allowing frost to build up.

Fan Mode is On

Some dehumidifiers feature a fan mode where the unit stops dehumidifying and only the fan is running. It could also be that your dehumidifier has already reached your preferred humidity level and has stopped dehumidifying. If only the fan is running, it increases air circulation in the room and it could make the air feel cooler to you.

Frozen or Dirty Coils

When the air cools down, moisture condenses on the coils, which can disrupt the airflow and cause the dehumidifier to ice up. Afterward, the coils reheat the air but if there is any blockage inside, it can compromise the refrigerant system, allowing frost buildup on the coils. That’s why you must keep the air filter clean to protect the coils. If auto defrost doesn’t work, the dehumidifier will continue passing the air over the frozen coils, producing cold air in the process.

Other Mechanical or Electrical Failures

Refrigerant dehumidifiers rely on refrigerant to facilitate the cooling system, so if the refrigerant leaks, it affects the whole operation. Furthermore, a broken compressor, faulty parts, or electronic malfunction can all lead to your dehumidifier freezing up. If there’s a buildup of frost or dirt on the coils, the compressor can become overheated. If you can find the issue yourself, it’s best to have the unit checked by a professional to assess the problem.

Water Restoration Dehumidifier

How To Fix A Dehumidifier Blowing Cold Air

Once you’ve found the cause, here are some ways you could fix your dehumidifier, starting from the easiest steps to take.

You must first check the temperature in the room. If the temperature is below 65°F, chances are, your dehumidifier will start to decline in performance. Even colder and the moisture might freeze on the coils instead. If your refrigerant dehumidifier is functioning properly, it should activate auto defrost to remove any ice buildup before resuming normal operation. If the unit does not defrost automatically, you should check and turn it off manually. Wait for the ice to melt completely by operating in fan mode or using a separate fan or heater. 

In any case, you might not even need to use a dehumidifier if the air is already cold and dry. To avoid frozen coils, don’t use the dehumidifier in low temperatures, to begin with. Check the temperature as well as the humidity to determine if you need a dehumidifier at all. Most manufacturers indicate the recommended operating temperature and you must follow these instructions. 

Once you’ve checked both the temperature and humidity in the room, you must also make sure the dehumidifier is free from any blockage to the airflow. Keep a distance away from walls, furniture, and other objects to provide enough air circulation. 

If you notice dirt on any part of the dehumidifier, unplug and wipe down any dust, dirt, or debris that is blocking the air inlet or outlet. Clean the filter to prevent impurities from entering the unit. For more specific instructions on proper cleaning and dehumidifier maintenance, check your manual.

The dehumidifier coils also need to be cleaned periodically to reduce particle accumulation and protect the compressor from overheating. You can do it yourself by vacuuming the coils with a brush attachment, but before you do so, check the manual for guidelines. It’s always best to hire an expert for professional cleaning services.

In some cases, the dehumidifier may remain on defrost mode even if there is no frost inside. If you’ve done all the routine maintenance and this still happens, try to restart the unit and check the manual for specific troubleshooting steps. If the temperature is above 65°F and the unit is still on defrost, there might be a problem with the humidistat or thermostat. In either case, do not attempt to fix it yourself and call a licensed technician to get your dehumidifier examined as soon as possible.

Dehumidifier Blowing Cold Air

FAQ

Does a dehumidifier make the room cold?

While a dehumidifier typically consists of a refrigerant system similar to air conditioning, it does not cool the air to the same level. However, it does reduce moisture levels, increasing your comfort and making the air feel cooler.

Do dehumidifiers heat up a room?

It does not necessarily heat up a room, but it actually produces air that is about 2°F to 4°F warmer than the inlet temperature. This is because it pulls moisture from the air and warms it up in the process.

Why is my dehumidifier blowing hot air?

Usually, it’s simply because the air coming from the room is also warm. For almost the same reasons a dehumidifier is blowing cold air, a dehumidifier may blow hot air when the filter or fan is clogged and there is not enough airflow. 

What should I set my dehumidifier at?

The ideal indoor humidity range for your home is between 30% and 50% RH. In most cases, 45% is the best setting, but it can depend on the ambient temperature. When the air is significantly cooler, you will need to set the humidity lower.

Should you run a dehumidifier constantly? 

There is absolutely no reason to run your dehumidifier all the time. Ideally, you should only run the unit when the humidity level is higher than 50%. Constant use of your dehumidifier can be inefficient and even harmful when it dries up your home too much. However, some units are designed to shut on and off automatically to manage this for you. 

Conclusion

In general, dehumidifiers naturally produce heat when running. They work less effectively as the temperature decreases and may start to form frost when temperatures drop below 65°F. When the air is too cold, the exhaust air may also be cold and this is perfectly normal. Refrigerant dehumidifiers usually have an auto defrost feature to prevent frost buildup. During defrost, your dehumidifier may produce cold air while it runs the fan only to melt the ice inside. If you notice frost inside and auto defrost isn’t working, stop operating and perform the appropriate steps above or consult your manual. Conversely, if your dehumidifier blows hot air, follow this guide we have for this situation. If you can’t find the problem, call a professional to check up on your dehumidifier.

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