I had the unit running for 2 days straight on the low setting. On the 3rd day, large amount of ice on coils formed and would not defrost automatically. The temperature in the room was 60 degrees F. How can this be avoided? I want to keep the unit running 24 hours a day until the moisture is gone in the basement. I don't want to have to stop the machine to defrost all day long. Any suggestions.
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when ice forms on an evaporator unit (coil) there is an indication of internal problems with the unit. IT may occur if there is insufficient air flow ( dirty or fan speed to low ) but when this happens the thermostat just orders more gas through the tx valve and so more ice is formed then the thermostat reads it as too cold and so cuts the gas flow back by controlling the operation of the tx valve
Water from a dehumidifier will depend on the atmosphere humidity so the lower the humidity reading the less water collected
However I suggest that you have a technician check it out as the compressor start/run capacitor may be faulty and that is why the compressor is not getting hot as it may not be running properly
the coils freeze up for one of two reasons .. if air flow is blocked .. sometimes by dust buildup or fan bearings needing lube .. second if the fan is working properly then ice buildup can be caused by low refrigerant levels .. the proper charge produces a steady coolness across the entire evaporator (cold coil) .. as the level drops it tends to cool a small part of the evaporator way too cold .. that creates ice .. the ice blocks the air flow and soon the whole thing is blocked ...so check the fan first .. if its running properly and there is nothing blocking air flow then suspect low refrigerant.. that requires adding a saddle valve service port to the system to allow adding refrigerant .. often the problem is caused by the fan not working at all because of lack of lube in the bearings or a bad starting capacitor ..
Your post says you have an RX but the picture shows a SantaFe Classic.
In either case the massive frost build up is caused by a defective defrost thermostat. PN 4021470 Parts Dept 800-533-7533 x 8451
The defrost thermostat has an internal set of electrical contacts that are designed to open up and turn the compressor off when frost or ice has accumulated on the tubing and the evaporator coil. If the contacts fail to open, the compressor keeps running and the frost and ice just keep accumulating until such time as the homeowner unplugs the unit or a sevice tech replaces the defrost t-stat.
Thermastor Service Dept
800-533-7533 x 8459
I did a little digging around on the internet and found out that if the basement (or where ever you have your unit) is in an area where the room temp might dip below 65 degrees the coils may start to become "too efficient" in pulling the moisture/humidity out of the air and it begins to freeze on the coils before it can drip off into the reservoir. The site said to turn off the unit and let it thaw out, then restart it and see if everything works ok after that. If the temperature gets too low you might need to warm up the air in the room/basement before it will operate correctly again/not continue to freeze up. Hope this helps. Mine just did the same thing but we've had some pretty cold weather recently and the basement is fairly cold as well.
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.