Author Topic: Dehumidifiers  (Read 377 times)

plongeur66

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Dehumidifiers
« on: August 10, 2016, 04:47:26 PM »
So I've accumulated 3 of these "lucky goldstars":

One I curbed 3 months ago. Another came from a roll-off behind a strip mall. The third one has been around long enough for me to forget it's place of origin.
Time to play a game of "Fix It Or Toss It!"
The curbed one runs, but the control buttons sometimes have to be pressed repeatedly. I open it up and see lots of dust on the coils. Easy to remove with a toothbrush:

I take apart the control panel and check the microswitches with my ohmmeter. Switches are good, but I see a corroded trace on the board:

I bridge the corroded trace with a short piece of insulated wire. Unit responds consistently now.
Time to check the refrigerant charge without attaching gauges or otherwise breaking into the sealed system. Ambient temperatures were ideal for this test - between  75 and 85 degrees.
The fat section of pipe alongside the compressor is a "suction accumulator" designed to make sure liquid refrigerant doesn't get into the compressor:

This should be cold after the unit has been running for a half hour. Air temperature matters - low temps can make a partially discharged unit look good...high temps can make a good unit seem low. This unit checked good, on to number 2.
No power to this one. I first check the AC voltage coming off the transformer. Checks good at about 16VAC. Then I check the DC voltage across the capacitor behind the voltage regulator:

The expected 12 volts means the regulator is working correctly. Some of the microswitches on this unit's control panel were intermittent. I slid a screwdriver blade across the terminals of the power button....and the unit roars to life.
I spray some contact cleaner into the switches while rotating the buttons by digging my fingernails into their edges. Switches seem OK afterwards, but I unsoldered the "Humidity Up" and "Power" switches and interchanged them. I run on "Max Dry" whenever I need to power up the unit, so it won't matter to me if the former power switch acts up again in it's new place.
Unit # 3 had a similar problem. Intermittent switches and a couple of corroded traces on the board:

Corroded traces were very short and didn't cross over anything on this unit. I just took single strands of bare copper wire and soldered them down. Sprayed a small amount of acrylic sealer to waterproof. All units are working fine, I now have 3 spares for the Haier unit I've been using. I tossed an older mechanical Fedders unit that had an open-circuited de-icer switch.
« Last Edit: August 10, 2016, 04:52:09 PM by plongeur66 »

Scav

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Re: Dehumidifiers
« Reply #1 on: August 11, 2016, 06:00:11 PM »
I found a unit very similar to the one on the right. Same issues with intermittent buttons. I was selling it so I replaced the board for something like $8.

Very nicely documented repairs. I'll have a go at bridging corroded solder joints in the future.