Sears dehumidifer problems

[GregS]

a friend who works for sears reported getting may dehumidifers back and
finding the digital control boards failed often.

see the store they might just give you a new one if its the bad model...

Now the cheap way to get a really good dehumidifier, buy a $85 LG 5000 BTU
airconditioner, and use it. Just hook up a drain hose. OK you also put it in a window
in summer.

greg

 

[Fred McKenzie]

The humidity setting is via a digital touch panel in front. I don't see
any way to tweak the adjustment as the sensor assembly is simply attached
by a long cable to the back of the PC board on the control panel.

Mike-

After setting, does the touch panel read out its version of actual
humidity? If it only shows the set point, you don't know whether it is
shutting off because it has reached the set point, or because the
compressor has shut down from an over-current condition.

It might just be a coincidence that the cycling compressor appears to
maintain a particular humidity level.

Fred

 

[Sam Goldwasser]

Why does ice indicate low coolant?

If there isn't enough coolant, it basically expands and cools without
filling the entire evaporator coil and it gets colder in that limited
area.

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[Mike S.]

Mike-

After setting, does the touch panel read out its version of actual
humidity? If it only shows the set point, you don't know whether it is
shutting off because it has reached the set point, or because the
compressor has shut down from an over-current condition.

It only displays the chosen set point; not the actual humidity.

It might just be a coincidence that the cycling compressor appears to
maintain a particular humidity level.

Hmmm. in any case, I'm replacing the sensor, so it should eliminate that
variable.

 

[William R. Walsh]

Hi!

It's quite possible for these things to shift calibration. It's probably
just a strip of a plastic-like material (used to be human hair but I don't
think they use that anymore!) that changes length depending on humidity.

Wow...I never heard of one using hair as a humidity indicator!

This must not have been done in a long time, as I've got a Sears Coldspot
dehumidifier that's at least 30 years old and it uses a conventional thin
layer of plastic in the humidistat.

William

 

[Shawn D'Alimonte]

I haven't removed or opened it. It's a small white box with a grating in
front, sort of looks like those little piezo sound transducers. Has a
3-pin connector on the bottom. Will look more closely when I open the case
to install the replacement.

If it is the style I am familiar with it acts as a variable capacitor.
Something about a membrane that absorbs water with an electrode on each
side. When I used one it was in an oscillator circuit with a
microprocessor measuring the frequency. They are non-linear and
somewhat temperature dependent.

 

[Dave M.]

[email protected] (Mike S.) wrote in

[I've cross posted this to what seemed to be the most appropriate
places; no flames please]


I have a 4-year old Kenmore 65-pint dehumidifer which sits in a
basement room containing electronics, etc. and I keep the relative
humidity below 50%. It has functioned well until I turned it on for
this summer season (in the winter, hot air from the furnace keeps the
room dry as a bone). Nothing has changed in the room, or the basement,
which would affect the ease with which humidity could leak back into
the room.

I keep a digital thermometer/hygrometer in the room (double-checked
for accuracy with another unit elsewhere in the house). The problem
seems to be the (digital) humidistat (which has a range of 40 - 60%)
which now seems to be about 10 - 15% too high. As a result, even with
the dehumidifer set at 40%, the steady-state humidity in the room
barely goes below 50%.

I checked the warranty and it only applies to the sealed components
(condenser, compressor, etc) so I opened the unit and found no
evidence of a humidistat adjustment or trimmer. The humidity sensor is
mounted on the inner frame of the unit, within the stream of air flow
between back to front, next to the sides of the coils. When it has
stopped running at an ambient humidity of 50% (even though set to 40%)
it restarts again when I blow moist air from my mouth at the sensor.

It looks to be sourced from LG, and browsing in stores I see newer
units which allow set points down to 30% relative humidity, as well as
low temperature operation. I'm toying with the idea of simply
replacing the unit, but wonder if it's worth the expense of having a
non-warranty failure repaired - or the hassle of ordering a
replacement sensor and trying it myself.

Any thoughts?

Mike,

I went through 5 dehumidifiers in one summer due to bad humidity sensors.
I then found gas leaks at a few black pipe joints. "Knock on wood" the
latest dehumidifier has not changed since new, but I have to set it at
35% to get 66% humidity (an obvious calibration offset) . If the gas
polution wasn't the cause, There is a really bad quality issue with
dehumidifiers with many manufacturers, I.E. Maytag, LG, Goldstar,
Whirlpool and GE with the above humidity accuracy problem. The humidity
readouts just pegged at the top of the scale and the compressors would
not run.

I wish I could find a good old horses hair or cellophane humidistat
controled unit!!

Dave M.

 

[Don Wiss]

a friend who works for sears reported getting may dehumidifers back and
finding the digital control boards failed often.

see the store they might just give you a new one if its the bad model...

You will get better results if you write to the Sears president. Someone in
his office will take care of the problem.

Don <www.donwiss.com> (e-mail link at home page bottom).

 

[Mike S.]

If it is the style I am familiar with it acts as a variable capacitor.
Something about a membrane that absorbs water with an electrode on each
side. When I used one it was in an oscillator circuit with a
microprocessor measuring the frequency. They are non-linear and
somewhat temperature dependent.

I was hoping you'd say there is a trimmer adjustment on the back ....

 

[Sam Goldwasser]

I was hoping you'd say there is a trimmer adjustment on the back ....

But if it is a capacitor, you could add a trimmer or fixed cap in series
or parallel to change the setpoint.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

 

[Mike S.]

But if it is a capacitor, you could add a trimmer or fixed cap in series
or parallel to change the setpoint.

Thanks for that .. when swap in the replacement I will examine the
existing sensor for possible future intervention.

 

[Mike S.]

Follow-up to this thread: Basement getting awfully damp while I wait for
the replacement sensor. In the end I took it to Sears for an estimate.
They acknowledged that it had 1 year remaining warranty on the sealed
components (but not the rest). Today (2 weeks after drop-off) I received
two messages from Sears on my answering machine.

The first message was an apology for the delay, and they would be
contacting me soon.

The second was a statement that Sears had decided to replace the
dehumidifier rather than attempt repair; and I would be notified shortly
when to pick up the new unit.

When I pick it up, I'll turn in the sensor for credit. All's well that
ends well ... though I suppose I won't know for sure now whether the
problem was the coolant or the electronics/sensor.