My Frigidaire dehumidifier compressor runs constantly and will not turn off with the switch. Have to unplug the unit.. Everything seems to be working to dehumidify. Is this a bad motherboard?

So I just had this happen with my Frigidaire fad704dwd dehumidifier. I went to basement and heard it running and sounded off. The compressor was running fan was off which is bad and humidity said 30. I then pushed the off button and it stayed running. I was able to fix it. To make long story short it was a bad ground. I took the plastic back, sides, and front off. There was a green ground (main ground) and Green/yellow ground (fan ground) on the front coil with a bunch of rust. Removed the grounds connected them both together and cleaned the surface area and used a new stainless screw nut and screw to remount the wires to evaporator coil. Everything started working fine after that and I put it back together. Good Luck

Starting relay, capacitor bad.

Good Afternoon Desi,

I understand that the blower wheel is not spinning on your Frigidaire dehumidifier, model# FAD504DUD. I also see that the compressor will stay on unless the dehumidifier is unplugged. I suggest you contact the manufacturer for further assistance. They can possibly clarify why the compressor stays on and why the blower fan is not working. If not, they should at least be able to point you in the right direction of having your dehumidifier working. Hope this is helpful.

-Best Regards-
WP

First, I'm not a Frigidaire tech.
* Check your warranty. Call for service.
* Contact (note Live Chat link); https://www.frigidaire.com/Owner-Center/Contact-Us/
*** following is for information only ***
* Check by setting to "Driest" or max setting. It should stay on longer.. If not then there may be a problem with the air sensor. Call for service.
* If the compressor keeps turning on and off every 2 mins then it may be "short cycling". Call for service.
* Be sure to check the tub and filter (make sure they are seated properly.)
* Checking basic problems; https://www.youtube.com/watch?v=SXJrVGP_Ixs
* Review; https://www.youtube.com/watch?v=BbwIEU3zlG8
Aloha, ukeboy57

Have same issue with 3 year old Frigidaire dehumidifier purchased in 2012. Must unplug to stop compressor running with power switch turned off. Unit gets hot and smells. Unplugging creates arcs at outlet since unit is pulling a lot of power. Plugging back in after some hours will make it appear to run normally and again remove moisture but it will not shut off when the fan goes off (humidistat bad?) and the set-point is reached. Cannot leave plugged in due to safetty/fire/overheating concern. Have not found answer on this forum or any other so far.

If you have a dehumidifier that is not producing any water then you are wondering what you need to do to get this thing to work for you. In some cases you may be able to do something and in other situations there may be nothing that you can do.

If you do not hear the compressor running and the unit says that the humidity in the room is higher then the setting, then you have a problem with your dehumidifier.

A few things that can cause this are:

The circuit board relay has gone bad...replacement of this board will often cost more then a new unit. This also is a very common problem with many dehumidification units.

The compressor has failed...if you hear a buzz for a few seconds, every few minutes, then you have a bad compressor or at least bad start components on the compressor. Either way it again is a costly repair.

If the compressor is running and the coils are not getting cold then you have a refrigeration system leak. Recharging or fixing these units is very difficult and is another costly venture compared to the price of a new dehumidifier.

If the compressor is running but the fan is not, this also will cause low water production and continual freezing of the coil.

If the compressor and the fan are running but the coil is totally blocked then you will get no water production. Air needs to be continually moved over the cold coil to get the water out of the air.

If nothing is running, then you may also have a control board failure. Or the humidity sensor or humidistat has gone bad which tells the machine to run. If the sensor says that the humidity is low enough then it will never run.

Also if nothing is running check the float switch or the bucket switch. Many of these switches are very touchy and if you do not have the bucket in place just exactly right it will not trip the switch to allow the unit to run. These switches often are more fragile then they should be and break easily. The good thing is that when available they are easy to replace and relatively inexpensive.

There are some parts available for a few brands, but with the prices for most of the parts that you can replace running anywhere from 40.00 - 80.00 dollars, replacement parts with labor to install them, makes a repair more then the few hundred dollar cost of many of these dehumidifiers.

As you can see there are quite a few things that can cause your dehumidifier not to work. Systematically go through the list and eliminate things to get to the bottom of the issue causing your problem and then decide if it is worth spending the money to try to fix the old unit. Only you can make that decision.

Part of the problem may be that you have the humidity level set to high. The fan runs constantly to move the air around. When the unit senses a humidity level higher than what you have it set for, the compressor turns ON. Once it's ON, if the humidity level is short lived, it turns OFF.

Try setting the humidity level to the lowest possible setting. Usually, that 45%. If the humidity level in you home is higher than that, the compressor should turn ON and run until either the bucket is full or the humidity level reaches 45%. If this doesn't solve the problem, turn the Master ON/OFF Switch to OFF and unplug the unit from the wall outlet for 12-15 minutes. Plug the unit bakc in, turn the Master ON/OFF Switch to ON and set the humidity level at it's lowest setting. Allow the unit to run until it cuts OFF and check the bucket for water. Hopefully that 12-15 minute time out allowed the unit to reset itself.

Hope this helped you to troubleshoot and solve the problem. Please let me know. Thanks.

remove the back airfilter, and touch the tubes while the unit is running, if nice and cold, all is well, there just isnt any moisture there. but if compressor is running and tubes are warm , means freon/coolant has leaked out

You have to remove the entire wrapper to get to the control circuit board, make sure you unplug unit!! Locate the small white wires that plug into the board and go to the humidity switch.Unplug the connector at the board and plug the machine in and see if everything runs. ps make sure you reinstall the bucket or unit will not run. If machine runs replace that humidity control. The plug on the board is usually white. The other white wire is 4 the light. I hope this helps./

I just picked one up at a tag sale, seller said it worked sometimes. Seems to have the same problem as yours. I took the time to tweak all of the connections and then re-soldered the control board with no luck. I finally disconnected the humidity control and it worked fine. By disconnecting the humidity control the unit defaults to it's highest setting and you have to unplug the unit to turn it off. Conclusion so far is that the humidity control rheostat is bad.
Note: Now while running the fan runs continuously and the compressor cycles on and off every 10 to 15 minutes. This may to be normal since the unit appears to be doing its job and I'm not sure how it is supposed to run since a purchased it broken.