Dehumidifier Compressor Not Working?

So, your dehumidifier, which was running just fine, has suddenly stopped collecting water. You can tell it has stopped running because it’s been several hours since you last emptied the tank. Or, if it’s a continuous drain model, you can’t see the water flowing from the tank.

Worse still, your home feels too humid, which is made worse by the hot weather. The walls are sweating, and your windows are covered in fog.

What could be wrong? Why did the dehumidifier suddenly stop working? Why is it not removing moisture?

Desiccant vs. Compressor Dehumidifiers

First off, it’s important to understand why the compressor is the likely culprit when the dehumidifier is running but not removing moisture.

There are two broad categories of dehumidifiers – desiccant and compressor. Desiccant dehumidifiers are a relatively new breed that uses a desiccant wheel to extract moisture from the atmosphere. The wheel is generated by an inbuilt internal heater that allows the process to run continuously. Most desiccant dehumidifiers use silica gel as desiccant material.

Desiccant dehumidifiers are quieter than their compressor counterparts. They are also more compact and work well in both cold and warm climates. However, they aren’t yet widespread. Very few people have desiccant dehumidifiers.

Compressor dehumidifiers are the default option. If you have a dehumidifier in your home, there’s a 99% chance it’s a compressor model. Although they work best in warm climates and not so well in cold regions, compressor dehumidifiers are easy to maintain and more affordable. They are also easier to diagnose and repair in case of an issue. These reasons make them very popular.

How Compressor Dehumidifiers Work

Compressor dehumidifiers operate almost like air conditioners. The only difference is that they don’t cool air as much as air conditioners. However, just like the air conditioner, they rely on a refrigeration mechanism to extract moisture from home.

A compressor dehumidifier comprises five main parts;

  • A compressor unit compresses and expands a refrigerant gas (Freon is the most commonly used refrigerant) to cool the dehumidifier coils.
  • Compressor coils: Compressor coils serve as pathways for refrigerant flow around the dehumidifier.
  • fan helps draw warm, moisture-laden air into the dehumidifier and blows out cool, dry air back into the room via a different set of ducts.
  • A re-heater: Most dehumidifiers comprise a re-heater element to capture and collect heat generated from the cooling process.
  • A water reservoir is a small tank inside the dehumidifier that collects condensed water from the dehumidification process.

The working mechanism is straightforward. When you switch on the dehumidifier, the fan draws warm, moist air into the unit via the first set of ducts. This air is then passed over icy condenser coils. As the air passes over the coils, the moisture in it condenses, forming water.

Next, the water is collected in the reservoir tank while the now-dry air is blown out via a second set of ducts with the help of the fan.

The condenser unit sustains the cycle by cycling refrigerant through the condenser coils to ensure that the coils are icy at all times.

It can pump the refrigerant faster or slower to increase or reduce the dehumidification rate, depending on the relative humidity in your home. On a very humid day, it pumps refrigerant faster to remove more moisture. However, on drier days, it cycles slower. Readings from the humidistat determine the speed.  

Why the Issue Is Likely a Compressor Malfunction

From the above discussion, you can tell that a dehumidifier malfunction is likely a sign of compressor failure or malfunction.

  1. Nearly 90% of dehumidifiers in use today are compressor dehumidifiers. Very few people use desiccant dehumidifiers.
  2. The compressor unit is the heart of the compressor dehumidifier. Although other parts are vital, too, it runs the dehumidifier.
  3. The compressor is a very delicate unit. For one, it comprises many components designed to interact with precision. It takes just one misstep or error for the entire unit to malfunction.

7 Reasons your Dehumidifier Compressor Can Malfunction

Now that you know how compressor dehumidifiers work and why a malfunctioned dehumidifier almost always points to a compromised compressor unit let’s find out what could go wrong in the dehumidifier. A dehumidifier compressor can malfunction for seven main reasons;

1. Low Refrigerant Levels 

When the dehumidifier keeps running without changing indoor humidity levels, the most common culprit is refrigerant levels. As we’ve seen, compressor dehumidifiers run on refrigerant – usually Freon.

The refrigerant is the lifeline of the dehumidifier. It keeps the dehumidification process going. As such, when there’s a noticeable drop in refrigerant levels, the whole process is compromised. Low refrigerant levels typically result from leaks at the compressor and the coils.

An HVAC professional can fix refrigerant leaks with ease. Just make sure it’s done on time. Otherwise, it can cause significant issues and even damage the dehumidifier.

2. Overload 

Another common problem is damage to the overload switch. The dehumidifier’s overload switch protects the compressor from becoming damaged. It does so by protecting the compressor motor from current overload. So, if there’s excess current to the compressor unit, the overload with disengage so that the excess current doesn’t reach the motor.

However, this overload can malfunction too. For instance, it can be damaged by excess current. Or its electrical circuit may fail. If the overload is damaged, an electric current cannot pass through to the compressor. Thus the compressor won’t run no matter how hard you try.

3. Failed Compressor Capacitor 

The compressor dehumidifier contains two essential capacitors, i.e., a compressor capacitor that helps run the motor and a fan motor capacitor that helps run the fan. The compressor capacitor stores the charge needed to start the compressor. This helps to protect the capacitor motor while ensuring a consistent supply of current to the compressor.

If the capacitor is damaged, the compressor won’t start. Usually, you’ll find that the unit trips every time you try to start it. A common reason the capacitor may fail is when the compressor air vent/grill is filled with debris collected over time. An experienced HVAC professional can diagnose and fix the issue with ease.

4. Electrical and PCB Issues 

Finally, the dehumidifier can also fail if the electrical circuits or the PCB board fails. The electrical circuit board contains all the circuits that control the dehumidifier function.

It has dozens of wires connecting to it and running to other dehumidifier parts, including the compressor. If either the wires or an element on the board malfunctions, the compressor may fail.

For instance, if a wire that connects the compressor unit to the circuit board is loose, the current flow would be cut. Therefore, the compressor will not start. The same applies if the PCB board is corroded or broken.

Other Reasons a Compressor Dehumidifier Can Fail

Besides low refrigerant levels, overload switch failure, a malfunctioned compressor capacitor, and a damaged compressor, a compressor dehumidifier can also fail for the following reasons;

5. Float Assembly Issues

The float assembly is a unique mechanism within the dehumidifier that signals the compressor when the tank is full. Remember that most dehumidifiers go off automatically when the tank is full.

This is only possible because of the float assembly. The assembly will instruct the compressor to turn off when the tank is full and send another signal to resume compressor operation once the tank is drained.

If the float assembly is broken, the compressor may not receive a signal to resume operation. Thus, it may refuse to run even when you switch it on. Float assemblies can be broken, blocked, or malfunctioned. Fortunately, they are easy to replace.

6. The Humidistat has Failed

All dehumidifiers rely on a humidistat to operate. The humidistat tells the unit when to run and when to stop. It also tells your humidifier how fast to run. Humidistats communicate directly with the compressor unit.

When it’s very humid in your home, they tell the compressor to pump refrigerant faster for faster moisture removal. They also stop dehumidification by instructing the compressor to stop pumping refrigerant.

As such, a humidistat issue will directly affect the compressor unit. For example, if your compressor isn’t running, the humidistat is likely not sending a “run” request. Therefore, similar to the float assembly, you can easily diagnose and replace the humidistat.

7. Malfunctioned Sensors 

In addition to the humidistat, dehumidifiers have sensors to monitor other environmental factors, including relative humidity, temperature, and airflow. These sensors are primarily designed to boost accuracy and efficiency. They closely monitor indoor conditions to ensure that the dehumidifier maintains the perfect humidity levels for your utmost comfort.

These sensors also primarily communicate to the dehumidifier via the compressor unit. They are typically found on a control board that directly connects to the compressor unit such that any environmental changes are quickly factored into dehumidification rates. Thus, malfunctioned sensors can compromise compressor function, possibly causing the unit to run without removing moisture.

Consider Professional Diagnosing and Repair

Although it might be tempting to diagnose and repair a malfunctioned compressor dehumidifier on your own, the appliances are too delicate for DIY. The compressor unit, specifically, is a very sensitive area. So it’s best to bring in an HVAC professional to take a look.