The unit is icing up - Frigidaire FAD704TDD Dehumidifier

Hi,

Here is a tip that I wrote that will help you understand why and what you cando with a dehumidifier that ices up.

Dehumidifier is Freezing up and not working

heatman101

The air intake filter may be clogged. Cleaning it, may solve the problem, once the unit thaws out. In addition, low refrigerant gas can also cause the unit to ice up. While waiting for the unit to thaw completely, turn the Master On/Off Switch to OFF and unplug the unit. In addition to thawing this unplugged time, may give the unit a chance to reset itself.

Hope this helped you solve the problem.

Hi,
Dehumidifiers freezing up can be causes by a few different problems.
Here is a tip that I wrote to help people with the freezing dehumidifier problem....

Dehumidifier is Freezing up and not working
http://www.fixya.com/support/r4662033-dehumidifier_freezing_up_not_working

heatman101

You've developed a sealed system problem.

timer is not working, or thermocouple is defective.
unit must cycle forward-reverse to remove ice, thisis how it works, by melting the ice that forms.

You are operating the unit in a cold location.wait until it is warmer or move the unit to a warmer location.

Hi,
The unit may be leaking freon...
Here is a tip that I wrote that will help you understand why and what you cando with a dehumidifier that ices up.

Dehumidifier is Freezing up and not working

heatman101

Three possibilities for coils icing up.

1. Low ambient temperature in the area where dehumidifier is located. If so, shut down and de-ice it. Then move the unit to a different - (warmer) - location and start it up.

2. Heating element - (which cycles periodically to liquify frost on the coils and allow water to drain) - is malfunctioning.

3. Low refrigerant level in the unit.

Depending on the location of the icing up unit, it may be in an area of your basement that's a bit too cool. These units are notorious for icing up under such conditions.

First, "defrost" the iced up unit completely using a hair dryer. Then swap its location with the other unit which is functioning normally. If that resolves the problem, then it was caused by the above "too cool" scenario.

If not, then it's likely that the thermal control which periodically heats up the coils in order to melt off the accumulated frost/ice and drain it has failed. Repair could be costly, and you're probably better off replacing the unit with a new one - - which you can find for less than $200.

My unit is a Fedders A7DH65B2A and your Maytag unit was made by Fedders and is just like mine w/ different label... I've purchased two of these units (one for me & one for my father-in-law) and they both quit pulling moisture from the air (but ran constantly) about 1 month past the 1yr warranty. My unit also acted really strange one day when the problem was occurring - it flashed on & off erratically and wouldn't power off unless I pulled the power cord. In short, I took it apart and found several issues and eventually figured out the chain of events that led to this: 1) The thermistor went bad and the unit could no longer sense when the evaporator coil started freezing up (normal situation that the unit should detect & then do a defrost cycle). As a result, the evaporator coil turned itself into a big chunk of ice (can see by removing the air filter and looking into that slot at the coil (looks like a radiator). 2) the big block of ice on the coil grew large enough to start making contact with part of the plastic housing above the evap coil that's used for the power control circuit board. The plastic in that area then got ice all over it and since it looks like a little tray, it will hold water (when the ice thaws) and then the power control board will be sitting in a puddle of water (or ice - either will cause malfuntions like not being able to turn the power off using the front panel switch). 3) the puddle of water in the power control board tray caused this circuit board to corrode (happens very quickly when the unit is plugged in since electricity accelerates this kind of thing...). So... a poor quality thermistor (this straps to the bottom right side of the copper pipe that loops out & back in to the evap coil and has a wire coming out of if) caused premature defrost circuit failure. This caused a big block of ice to form where it shouldn't be. The ice caused condensation/moisture/ice to form on/under the power control circuit board and corroded the circuit board and caused erratic power control issues. RepairClinic.com had a replacement sensor board (included all sensors - yes, the thermistor too...) so I purchased it (~$40) and used only the new thermistor off of it to plug into my original sensor board (and strapped it back to the evap coil w/ the chrome looking clip that was already there). Problem fixed! Well, almost... I did have to clean the corrosion off my power control board as well, but it survived luckily. After doing this to mine, my father-in-laws unit experienced similar symptoms. I did the same fix to his and presto... fixed. Cheap low quality thermistors on these units. I need to find a higher quality replacement thermistor before round 2 happens on each unit. Good luck!