Evaporator Icing I have a 2 year old LG dehumidifier. It is a low temp humidifier that refuses to go in to defrost. I put the sensor in a freezer and checked it with an ohm meter and resistance does change. (can't remember the numbers) If I unplug the sensor from the PC board (unit running and froze) it goes in to defrost. If I reconnect the sensor back up it will just freeze back up again eventually. I am thinking PC board failed but would like to be sure it is not the temp sensor first. Can you tell me the temp vs. ohms relationship of the sensor? That would be a great help.

The dehumidifier should be removing water at 66F 70%rh.

First make sure that the compressor and fan are running. If they are, then turn the dehumidifier off and unplug the cord from the wall outlet. Next remove the front cover from the dehumidifier. Examine the evaporator coil (about 1/2 way up) beneath the plastic heat exchanger and above the stainless steel drain pan.

If the evaporator coil is cold and completely covered with frost & ice, the defrost thermostat may be defective. Replace the front cover. turn the humidity dial to "off". Plug the dehumidifier in to the wall outlet and set the fan switch to on - the fan will run (no compressor). Run this way for one hour to defrost the evaporator. Now adjust the humidity dial to your desired humidity and keep an eye on the dehumidifier. If it freezes up again and does not automatically defrost, the defrost thermostat should be replaced. Call the manufacturer at 1-800-533-7533 for parts and instructions.

If the evaporator coil is (mostly) warm and free of frost and ice, it is likely that some of the dehumidifier refrigerant has leaked out. this type of service should be done by a (refrigerant) certified technician. Call the manufacturer at 1-800-533-7533 for help with this service.

According to your Owners Manual, the coils may start to frost at 60 degrees and the defrost sensor should turn ON and cycle periodically. However, the air temperature at the floor level in a basement, is colder than the air temperature by 5 to 8 degrees. So this may be causing the problem. In addition, if the air intake filter is dirty or clogged, the unit has to strain to keep up and will not function as it should.

If the unit is totally iced up, turn the unit Off and unplug it from the wall outlet. Allow is to thaw completely before attempting to clean the filter. You may want to put some old towels under it while it thaws. Once it's thawed, move it to a bathroom that has a shower. Plug it it in and set the humidity level at 45%. Turn the shower ON at a Medium hot temperature (enough to generate steam) and as you exit the batroom, close the door. DO NOT operate the bathroom's exhaust fan. Allow the unit to operate for 15 to 20 minutes, before returning to the bathroom. Then turn the shower OFF and check the unit for any frost and the amount of water collected in the bucket. If there is no frost on the unit and there's water in the bucket the unit is operating properly.

When you move it back to the basement, place it up off the floor on something sturdy, that can hold the weight and not be bothered by the vibration of the unit, when it's running. (ie a work bench, a counter top, etc.) Operate the unit as you normally do and monitor it for frost or icing up. And, whether or not the defrost sensor is cycling as it should. If you get no frost or just minor frost, it was the air temperature at the floor level, that was causing the problem.

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

The room temperature is probably too cold, or there's poor airflow
Here's some info that should help you figure out what's causing the problem:

If the evaporator coil is frosting completely and evenly, the most common cause is that the room temperature is too cold. Most dehumidifiers are not meant to be used when the room temperature drops much below 70°F and certainly not below 65°F (depending on humidity). There are however some models called "basement" dehumidifiers which are.

Another possible cause on standard models is poor air flow through the unit. If the fan motor is not turning fast enough (or at all) or the evaporator, condenser or filter (if used) being plugged can also cause this symptom .

Turn the unit OFF and unplug it from the wall. Allow it to thoroughly thaw and remove the humidifiers cabinet to expose the cooling coils. Clean those thoroughly and coat with a very light coating of WD40. Reassemble the humidifier and turn it ON. Set your humidity control at 50% and allow the unit to run for at least one hour. Check for water collection in the bucket and for any signs of icing, after one hour. If water is in the collection bucket and no signs of icing, lower the humidity to 45% and continue. If you not any signs of icing, watch the unit, as you need to know if it automatically goes into defrost mode. The compressor should shut off, but the fan will continue to run until defrosting is completed. If it doesn't the auto defrost sensor has failed and will need to be replaced.
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Hope this helps you to troubleshoot and solve the problem. Please let me know. Thanks.

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

vbn

Hi,
Here is a tip that I wrote about that problem...

http://www.fixya.com/support/r4662409-dehumidifier_running_but_no_water_in

heatman101

the unit either has dirty evaporator coils and this will make them ice up,or the unit is low on refrigerant/freon,try cleaning the whole unit of dirt and dust first,then you may need to install a saddle tap on the sealed system and add some refrigerant/freon as these systems seem to leak more often than other sealed systems

This will need to be serviced. LG has a 5 year warranty on these models. They usually will tell you of a service center nearby which will service it free of charge since it is under warranty. If you do not live near a service center they may ship you a replacement and you send your old dehumidifier back to them. Make sure you have your reciept when you contact them so they can verify it is 2 years old.

This will need to be serviced. LG has a 5 year warranty on these models. They usually will tell you of a service center nearby which will service it free of charge since it is under warranty. If you do not live near a service center they may ship you a replacement and you send your old dehumidifier back to them. Make sure you have your reciept when you contact them so they can verify it is 2 years old.

I have the same dehumidifier and it does the same thing. but I was able to fix mine. It was not low on refridgerant. There is a temp. sensor clamped to the evaporater coil with a thin metal clip. The clip rusted out and the sensor fell out of position. I used a small stainless steel hose clamp and clamped the sensor back into position. It now works fine