Will not shut off
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.
Apr 29, 2007 |
Maytag M7DH65B2A Dehumidifier