We have a Frigidaire wall unit A/C (10,000 BTU, 110V/12A unit)
that works fine, as long as we leave the thermostat turned all the way
towards cold. If we set the thermostat higher, as soon as the desired
temperature is reached and the compressor kicks off, we can tell by
the sound of the unit that it begins to pull way more amps than it should,
and the 20A circuit breaker on which it's located (the A/C is the only
device on this circuit, by the way) trips off within a few seconds.
We're curious if anyone here has seen this problem before, and if it's
likely to be an expensive fix. We don't mind just leaving the thermostat
all the way down, so the compressor stays on all the time, but still, the
circuit overloads are a bit disconcerting. We like to leave the A/C on
while we're out of the house and are worried about a possible fire risk.
Thanks for any info.
Could be the thermostat trying to re-stat the compressor. Normally, there
is a differential of a few degrees, but if it is faulty, it may trip, try to
re-start under pressure and trip the breaker. How old is the unit? Cold
be as cheap to buy new as to fix.
Sounds like a bad relay and/or pressure valve/sensor (if it has one).
It sounds like the unit kicks off, and then tries to restart the
compressor immediately. The internal pressure hasn't had a chance to
bleed off so the compressor can't kick over but keeps trying (pulling
a lot of power and probably making a low humming noise) until it pops
the breaker. Eventually this will burn out the compressor motor.
"I've been here, I've been there..."
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Gosh, I hate it when people multiple post instead of crosspost.
I already have replied to a thread, and then I see the same post
elsewhere a half hour later. Crossposting eliminates multiple
instances of the same article, and saves bandwidth and disc space.
Anyway, it could be the cold control.
The cold control could have a pinhole leak. It could be he diastat
has lost its working fluid, and is full of air at atmospheric
pressure. When it is run on "constant", the bellows is fully
expanded and the electrical circuit mechanically shorted. When the
knob is twisted, the switch is opened, and the bellows is compressed
against a spring. Normally, the pressure in the bulb would rise
when the bulb is heated, and drop when the bulb is cooled.
The more spring pressure against the outside of the bellows, the
higher the bulb temperature required toggle the switch. As the bulb
warms the pressure increases against the inside of the bellows, and
closes the switch, turning on the compressor. If the diastat loses
its fluid, and is filled with air, then when the knob is twisted
toward warmer, spring pressure is increased against the outside of
the bellows, and the compressor kicks off, but due to the pinhole
leak in the diastat, air exits and quickly equalizes the pressure,
the bellows collapses, and the compressor kicks back on.
One way to find out is with the unit unplugged, remove the wires
from the cold control. Unclip the bulb and dunk it in cool (but not
ice cold) water. With an ohmmeter across the terminals, watch what
happens when the control is advanced from "constant" to "warmer".
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