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The Keystone KSTAD70A 70-pint Dehumidifier removes up to 70 pints of humidity from the air per day.

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KSTAD70B Compressor seems to stay on inappropriately, starting icing

Hi:

I have the Keystone Dehumidifier Model KSTAD70B, it is very similar to the ‘A’ version. It has recently started icing-up and it appears it will run the compressor even when the fan is shut off. In fact, recently while it was seeming to run normally (cycles always start OK) I tested it by pressing the power button on the top panel, the lights went off as did the fan but the compressor just kept going. Per the ‘block’ schematic on the machine it would seem it is the power relay sticking that would cause this problem. Has anyone else had this issue? Eventually the compressor does shut off but only after it gets really hot . Is the relay the likely fix? I`ve already ordered a couple on ebay for $3 to try.

Thanks!

Tom

Answer this question I have this problem too

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Found this in a search. Did the fix here work for you?

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HI David:

On my unit I ended up replacing the compressor power relay AND cleaning the temp sensor connections and it is working again. I really believe it was the connections for the sensor... I used some Deoxit Gold on the connections and it has worked perfectly ever since. If it goes out the same way again I will simply solder the sensor wires to the PCB. The connector pins on the PCB are poor quality for the sensor, they should be a gold alloy or similar to prevent corrosion. I would try this if your unit has acted similar, it is cheap and relatively easy.

Tom

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Mine is now doing the same thing. It continues to run even when the power button is off. Do you have any pictures or the parts numbers you bought to fix it?

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Hi:

To fix my unit I did replace the power relay but I really believe the fix was simply cleaning the contacts of the sensor that fits in a holder in front of the fins. From the back mine was on the left side. It was during my 2nd attempt to fix mine that I realized the connector & pins for the sensor are of poor quality, they should be gold plated. After using “Deoxit Gold” on the contacts the unit has run without further issues.

If you need more detail for finding the connection (in the steel covered box) please let me know and I will see what I can dig up. I also have a second power relay I bought if you want to try that route.

Tom

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CSmith:

Try cleaning the (Pipe) Sensor connection first, in the electrical control box...

From the manufacturer (Midea)

https://midea.encompass.com/Exploded-Vie...

1-866-646-4332

Monday through Friday 8 am to 6 pm EST

Saturday 9 am to 4 pm EST

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Very nice troubleshooting based on the block diagram. I would say that if it seems to ice up sooner than expected that the Freon is getting lower as this is a visual symptom to “Low on gas”. I would also say that the fan kicks off due to the low temperature due to the icing and the heat exchanger does not need cooling off by the fan. I also would guess that your relay is stuck closed but a good smack on the head should rattle its brain to let loose and shut down as expected for additional troubleshooting, give it a good rap.

Icing due to low gas or very high humidity and also give it a good cleaning as dust will help condense water that will not drain off like normal, the dust will attract the water and it will freeze due to low fan air flow being blocked by the dust again. Then due to your constant compressor running will cause the temp to drop as well.

So we will assume the overtemp switch is working as the compressor is shutting down when overheating, this will override the stuck power relay.

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Hi Duane:

Thanks for your answer! My original comment failed to post so I will try to recreate again.

The auto-defrost function would seem to happen regardless of whether the unit is low on Freon or had dirty coils. The coils are very clean, there are no air flow restrictions. This defrost function should turn off the compressor and turn on the fan, not the opposite, right?

Midea (makes Keystone) stated the Pipe sensor (the Defrost Sensor) could also keep the compressor running with the fan off. This too seems illogical since it should cause the above scenario... fan runs and compressor turns off for defrost.

After disassembly and inspection the unit has not malfunctioned. After reassembling the unit it has worked flawlessly for 36 hours, if the Freon was low wouldn`t it just keep freezing up?

Thanks, I`m just trying to understand this unit.

Tom

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You seem to have covered all bases here now, low freon would show signs of icing, with clean coils that will not allow water to collect and freeze along with allow good air flow.

One of my sayings is, if you took it apart and broke/fixed it then it must be something you touched. A relay works now, you properly installed a sensor that is a direct contact type Temp Sensor.

I believe that now you are more familiar with the system, if it stops working properly, you are well armed to find the actual problem.

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Hi:

To fix my unit I did replace the power relay but I really believe the fix was simply cleaning the contacts of the sensor that fits in a holder in front of the fins. From the back mine was on the left side. It was during my 2nd attempt to fix mine that I realized the connector & pins for the sensor are of poor quality, they should be gold plated. After using “Deoxit Gold” on the contacts the unit has run without further issues.

If you need more detail for finding the connection (in the steel covered box) please let me know and I will see what I can dig up. I also have a second power relay I bought if you want to try that route.

Tom

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