Many people equip their homes with dehumidifiers. They come in handy for those living in climates that are muggy or humid.
They are also great for people who suffer from asthma or allergies.
In fact, your home may need a dehumidifier if you notice a great deal of condensation on mirrors and windows, or you’ve been experiencing issues with mold or mildew.
Regardless of why you invest in a dehumidifier, they are great to have. However, it’s a major inconvenience when they stop working.
There are several common issues that occur with these machines.
Today we’ll discuss what these issues are and how to fix them.
Let Start With “How does a dehumidifier work?“
Sure, you’ve heard of a dehumidifier, but do you know how they work?
Basically a fan draws humid, warm air over a cold coil. The cold coil then condenses the moisture into a liquid.
The water is removed via a drain pipe. Next, the dry air passes over a warm coil and then added back into the room.
A dehumidifier is an important part of your air conditioning system, especially if you live in a climate with high humidity during the summer.
The unit will ensure the air that comes into your HVAC system isn’t too moist. When this occurs it can lead to erosion of parts and mildew and mold problems.
A dehumidifier relies on several important components to work such as a bucket switch, humidistat, and compressor capacitor. If any of these parts fail, the unit will stop working.
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Not to worry, keep reading to find tips on troubleshooting each issue and how to fix it.
Common Issues and Possible Solutions
Defective Bucket Switch
The bucket switch is a single pole, double throw (SPDT) device that tells your dehumidifier to shut off when the water collection bucket is full.
The bucket switch is activated by a float that’s mounted inside the bucket. The switch is then mounted directly to the dehumidifier frame behind the bucket.
Sometimes the bucket switch can fail. When this occurs it makes the machine think the bucket is full, when in reality it is not.
In the event this happens, you’ll want to check each component that works with the bucket switch. Here’s how to check each part:
To Remove the Float
- Disconnect the dehumidifier from the power supply
- Remove the bucket
- Drain any condensate that may be present in the bucket
- Remove the pin that holds the float to the bucket
- Remove the float through the access hole at the top of the bucket
To Remove the Bucket Switch
- Disconnect the dehumidifier from the power supply
- Remove the three electrical leads from the terminals on the bucket switch
- Squeeze the tabs together and push up on the switch from the bottom
How to Test the Bucket Switch
- Test the resistance present between the three terminals on the switch
- Use a multi-meter on the resistance scale setting
- The switch should be on “AT REST” position
- Resistance readings should be:
- Common – Normally Open = MAX resistance
- Common – Normally Closed = ZERO resistance
- If you have the switch arm DEPRESSED, readings will look like this:
- Common – Normally Open = ZERO resistance
- Common – Normally Closed = MAX resistance
- If your readings are not within these ranges you’ll want to replace the bucket switch.
A humidistat allows you to set a desired level of relative humidity for your home.
This part is made up of two components – a relay amplifier and a sensing element.
The sensing element features two alternate metal conductors, and when there are changes to relative humidity, it will cause electrical resistance between the conductors.
The relay amplifier measures the resistance created and sends a signal to the dehumidifier to turn on or off.
The humidistat works by monitoring the levels of moisture present in the air. When moisture levels get too high, the contacts close and allow the humidifier to turn on.
When the humidistat fails, the dehumidifier cannot run.
There are several things you should do to troubleshoot this issue:
- Is your dehumidifier set for a humidity level lower than the room?
- Check to see if the humidistat is properly lined up, and not touching a wet condenser or surrounded by damp air due to a dirty air filter.
- Does it have a refrigerant leak?
- Does it shut off periodically? It may be overheating and turning off. If so, try to conduct a power cycle.
- Check to see if the humidstat is encased in ice or dirt. Try to clean the humidistat and the filter to see if that fixes your problem.
- Use a multi-meter to test for the part for continuity. If there is none, replace the part.
Failed compressor capacitor
The capacitor helps the compressor run.
When you find that your dehumidifier is running and both exhaust/intake fans are running, it’s a good sign that the capacitor for the compressor is bad.
You may also notice that water is not being collected from the air, or the overload device keeps tripping.
If the capacitor fails it will prevent the compressor from rotating the refrigerant.
One of the most common reasons this part fails is the compressor grill/air vent is covered with dust and dirt that’s been collected over time.
There are several other reasons it can fail, including:
Failed overload device – This component keeps the motor from becoming damaged.
Faulty fan motor – The fan should spin freely, allowing ample airflow through the device. If the fan is barely moving or humming, it needs to be checked and possibly replaced.
Electronic Control Board – The control board tells the compressor when to start. If there is a problem with this part the compressor will not be able to start.
The easiest way to troubleshoot this problem is to test for continuity with a multi-meter. If you find there is none, you’ll need to replace the part.
Compressor overload protection defective
If the compressor is not working on your dehumidifier, and you’ve already checked the capacitor, the next step you should take is checking the overload protection.
Much like a thermal fuse on a dryer, dehumidifiers have what are called overload protection devices.
The overload protector is attached to the compressor, and works to detect excessive current overload or heat.
If the overload is actuated, the compressor will shut down, and automatically reset itself after it cools down.
The compressor will try to start after the cool down period.
The overload protector is found under the terminal cover. Here’s an easy way to gain access to this part:
- Disconnect the power
- Remove the terminal cover
To test for an overload, follow these steps:
- Disconnect the power
- Remove wrapper
- Remove Terminal cover
- Disconnect all wiring, and check the overload terminals using a multi-meter
- Be sure the overload is at room temperature when you attempt to check it
- It should read ZERO ohms. Any other reading signals this part needs to be replaced.
Here are some common reasons compressors overload:
- Low Voltage – Disconnect the machine and check the voltage going to your electrical outlet and the dehumidifier itself.
- Defective run capacitor (as discussed above)
- Dirty condenser or evaporator
- Insufficient amounts of air passing over the condenser
Evaporator fan motor not working
If you notice your dehumidifier is not making water, and you have already verified that the ambient temperatures is above 65 degrees Fahrenheit, you may be dealing with a faulty fan motor.
You may also notice that your dehumidifier coils are freezing up.
To operate optimally, a dehumidifier is required to have enough air blowing across the evaporator coils to prevent ice or frost from building up.
To troubleshoot this issue you’ll need to check the grille area to feel how much air is coming through.
If you feel little to no air coming through, check the filter.
If the filter is dirty, you’ll need to clean it. On the other hand, if the filter is clean, remove the cover and check the area around the fan.
Be sure to inspect all coils to ensure they are not being restricted with dirt or lint. If you find that they are, go ahead and clean them.
Check the fan to see if the motor spins freely, and that the blower wheel or fan blade is still firmly attached to the motor shaft.
Use extreme caution to prevent personal injury, and turn the unit on in the “fan only” mode. This will make it easier for you to observe the fan motor in action.
If you hear that the fan is humming or notice that it moves slowly, or not at all, then it’s most likely defective. It will need to be replaced.
It may still be defective even if there is no sound being made and the motor is not rotating. When this issue arises, you’ll need to check the part using a multi-meter. Do you have a dehumidifier that hasn’t been operating properly? Comment below and let us know what’s going on. We’re happy to discuss, and help you find a solution.