On 2010-10-14, whit3rd wrote:
On Oct 11, 6:56*pm, "DoN. Nichols" wrote:

[ ... ]


* * * * How old was the one which was freezing up?

About 10 years old; it might be that I've had a succession of cheapos,
but three (Kenmore on the outside, LG on the inside) models had
similar
behavior. The electric usage, too, was high (about $10-$30 per
month).
These had humidistat mechanical controls, I imagine a timer-cycle
unit could
handle the frost problem easily.

Not really. The problem is lower refrigerant pressure, which
results in a colder expansion coil (the cooling coil). When it is low
enough, the expansion coil is cold enough so humidity from the air
condenses on it and instead of following gravity to the drip pan, it
instantly freezes -- and somewhat insulates the coil from the air. This
progresses until the air can't flow through the coil -- so the thing
keeps running and consuming electricity, while not condensing much
humidity at all.

Yes -- with a long enough off cycle, the frozen water will melt
and run off -- but the duty cycle will be long enough so it will do
little dehumidification.

Do yours have valves to allow checking the pressure and topping
off the refrigerant? Depending on the age, you might need a license to
get the proper refrigerant (if it is any Freon, it is a controlled
substance these days because of the ozone layer hole. :-)

Good Luck,
DoN.

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