Whole-home dehumidifiers are a great way to overcome issues with high humidity in the summer. Whenever your AC is running, the dehumidifier will work to absorb much of the moisture from the air flowing through your ductwork. These units are typically installed within the return air duct, which means that they will lower the humidity level of the air before it flows into the air handler and over the AC evaporator coil.

A home dehumidifier works much the same as your AC system and uses refrigerant to cool air as it flows through the unit, which causes the moisture to condense on the dehumidifier’s evaporator coil. The fact that a home dehumidifier both absorbs moisture and slightly cools the air means it will also lessen the strain on your AC system and help to lower your cooling costs.

While home dehumidifiers are extremely effective, they can sometimes have issues where they stop collecting water. If you do ever notice that your home dehumidifier isn’t collecting water, here are the possible causes and what can be done to overcome them.

Clogged Drain Line

Most whole-home dehumidifiers have a drain line that empties out into the building’s sewer system. This drain line typically runs to a floor drain or possibly into a sump pump basin. Some home humidifiers have a water collection tank, but these aren’t as common since you would typically need to empty the tank daily as most units can easily remove eight to 10 gallons of water from a home per day.

On most units, the condensation that forms on the evaporator coil drips down into a drain pan and then flows out through the condensate drain line. In some cases, this drain line is connected to your air conditioner’s condensate drain system.

Many dehumidifiers have a float switch in the drain pan that will automatically shut off power to the unit if there is too much water in the drain pan. This is important as otherwise the drain pan could overflow if the unit continued to run. If you find that your humidifier isn’t collecting water, it may be that the drain pan is full and caused the float switch to trigger. The only reason that this would really ever happen is if the drain line is clogged and the water can’t drain out of the unit properly. In this situation, you will typically need to have a technician unclog the drain line and then reset the float switch before the unit again works as it should.

Frozen Evaporator Coil

Another possible reason your dehumidifier isn’t collecting water is that its evaporator coil is frozen. The refrigerant that flows through the evaporator coil is extremely cold and usually below freezing. As warm air flows over the coil, the refrigerant absorbs heat from the air and quickly gets much warmer. Whenever the unit is running, cold refrigerant constantly flows into the coil and hot refrigerant flows out. If there isn’t sufficient airflow or the unit has some other issue, the refrigerant can remain cold enough to allow the moisture that forms on the coil to start freezing.

The evaporator coil can freeze if the dehumidifier’s fan isn’t circulating enough air through the unit or because the unit doesn’t have enough refrigerant. Low refrigerant decreases the pressure in the system and causes the refrigerant to become much colder, which can lead to the evaporator coil quickly starting to ice up. The evaporator coil can also freeze when it is covered in lots of dust and debris. A thick layer of dust on the coil will insulate it from the air, which means that the refrigerant may not absorb enough heat and thus remain cold enough that ice starts to form.

Malfunctioning Fan

A malfunctioning fan can also prevent a dehumidifier from collecting water. If the fan motor has any issues that prevent it from running, no air will circulate through the dehumidifier. As a result, moisture won’t ever collect on the evaporator coil and the unit won’t collect any water. Depending on the specific issue and what model of dehumidifier you have, the solution may be to have the fan repaired or replaced. However, there are some units where the fan cannot be repaired or replaced, in which case you will need to have your entire dehumidifier replaced with a new unit.

Overheating and Other Compressor Issues

The dehumidifier compressor can also have various issues that can prevent it from circulating refrigerant through the unit. If the compressor motor doesn’t turn on when it receives power, it can also quickly overheat and trigger the unit’s overload switch. There are also times when the overload switch could be triggered by the unit running for much longer than it should. The overload switch is important for preventing damage and reducing the fire risk that can occur if the compressor starts overheating. When the switch triggers, the dehumidifier won’t run again until the compressor has fully cooled off to a safe temperature.

Compressor issues are something you will want to have taken care of immediately or else the unit could break down or the compressor motor could burn out. Depending on the specific issue, a technician may be able to repair the unit or you may need to have it replaced.

Faulty Start Capacitor

One of the most common reasons that the compressor won’t start and the dehumidifier will overheat is that the start capacitor is faulty. The start capacitor stores an electrical charge and works to supply the additional power needed for the compressor to turn on. The start capacitor can fail over time or have an issue that prevents it from either storing the charge or releasing it when the compressor needs to turn on. A faulty start capacitor is something that will need to be diagnosed by a technician. If the capacitor is faulty, it can easily be replaced so that your dehumidifier will work properly again.

Clogged Air Filter

Whole-home dehumidifiers have internal fans that draw air in from the ductwork and force it through the unit. However, they still rely on the HVAC blower since this is what brings air into the ductwork. If you don’t replace your HVAC air filter regularly, it can become extremely clogged and make it so that the blower can bring almost no air into the ductwork. The less air there is flowing through your ductwork, the less air the dehumidifier will be able to draw in. As a result, the dehumidifier may start to collect little to no water since very little warm air can be drawn into the unit.

A clogged air filter can also lead to the dehumidifier’s evaporator coil or your AC evaporator coil freezing. It will also greatly decrease the effectiveness of both the dehumidifier and your air conditioning, which is why it is important that you replace the air filter regularly. We would also recommend replacing the HVAC air filter as the first step if your dehumidifier ever stops collecting water.

At Bardi Heating, Cooling & Plumbing, we install repair and service whole-home dehumidifiers and a range of other indoor air quality equipment like whole-home air purification systems. Our team can also help if you need any air conditioning, heating or plumbing service in Norcross or the Atlanta area. Contact us today to schedule a service call or if you have any questions.

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