Portable A/C Compressor Cycles for No Reason

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Old 06-02-15, 03:49 PM
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Portable A/C Compressor Cycles for No Reason

I own this unit -- Soleus KY-80
http://soleusair.com/Manuals/2013%20...2012-12-31.pdf


When running, the compressor blows very cold and everything works as intended. However, after operating for a bit, the compressor cycles off... well before the target temperature is reached.

In about 3 minutes or so (I haven't timed it -- estimated), the compressor kicks back on without issue.

I suspect one of two issues:

- The unit "thinks" it has reached target temperature and shuts the compressor off. Bad or improperly placed thermostat?
- The compressor hits some type of temporary condition where it shuts off for protection -- overheat?


I haven't modified the thing, other than to install an insulation sleeve over the exhaust hose as it is very thin and works against itself.

The unit is of course out of warranty and at one time, did work properly. However, I only use it about 4 months out of the year and off memory, can't recall when this started occurring.. One theory I had is that the insulation sleeve on the exhaust hose may be acting to cause additional heat to the compressor? I read on another site a suspicion someone had that the exhaust helps cool the compressor.

In any case. Does anyone have thoughts?
 
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Old 06-02-15, 05:18 PM
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To rule out the thermostat, you could set it very low, as low as it will go. If the unit still shuts off early, then it's likely not the thermostat.
 
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Old 06-02-15, 05:21 PM
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I did that. It goes down to 61.. and the same issue occurs there... It's tough to see if that even helps the situation or not... but I'm not sure I have enough evidence to completely rule out the thermostat.
 
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Old 06-02-15, 05:23 PM
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All window and portable air conditioners have the temperature sensing bulb located very close to the evaporator (cooling) coil. In this location they are affected by BOTH the incoming room air temperature and the evaporator temperature. This is actually a safety feature to protect the compressor if the evaporator ices over.

Sometimes moving this sensor just an inch further away from the evaporator makes all the difference in the world. On the other hand, you might be experiencing an excessively cold evaporator for a couple of reasons, most likely a slightly low refrigerant charge, and in that case the action would be normal. The down side is if the refrigerant charge is low it also means there is a leak and that sooner or later the machine will simply not cool anymore. Repairs on these are generally not worth the cost and replacement is the preferred option.

If you replace the unit I strongly suggest buying a dual-duct model. Your idea of adding the insulation sleeve to the exhaust duct is good but the single-duct models exhaust conditioned room air for the machine's cooling with outside air entering the space as "make-up" air. This lowers the efficacy of the machine significantly. A dual-duct machine brings in outside air for cooling the machine and then exhausts it out the second duct. Dual-duct models also have the ability to re-evaporate the condensate formed from dehumidifying the room air and blowing that moisture out the exhaust duct and that means it is rarely necessary to empty the condensate tank or to run an auxiliary drain hose. Of course it is best to also add insulative sleeves to BOTH ducts for maximum efficacy.
 
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Old 06-02-15, 05:34 PM
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Furd,

I thank you for your well thoughtout response.

In the event I want to locate this sensor, what is the estimated likelihood that it is accessible and that I be able to identify it visually? Can you provide an example or description of what this might look like? Is it possible that this sensor somehow detached and essentially relocated itself in a worse spot?

It sounds as if re-locating this may be a last ditch effort in prolonging its usefulness... unless I am willing to deal with the unnecessary cycling.

I must say, when the compressor is on.. it blows quite cold.
 
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Old 06-02-15, 06:13 PM
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You may be able to see the thermostat probe through the intake grill on the front of the unit. It could be a small cylindrical piece, about 3/16 inch in diameter with a small cable attached or it could be just a cable with what looks like a little plastic knob on the end barely larger than the cable itself. Getting to it entails removing the entire case and that's about twenty screws or so.


There IS a possibility, I don't recall on my Soleus dual-duct model, that there are TWO thermostat probes, one being the aforementioned room air thermostat and a second one physically attached to the evaporator piping or maybe into a "well" soldered to the evaporator piping. If this is the case then you will have to live with it until it finally dies.
 
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Old 06-02-15, 08:48 PM
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Thanks again.

Peeked through the front... can't say I see anything.

Any serious exploratory work appears to be best saved for the weekend...
 
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Old 06-03-15, 03:44 PM
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I popped the filters off the back and looked in through the cracks...

I saw a yellow object, that looked very similar to the end of a plastic ballpoint pen (that isn't being used -- no "metal" pen point) in terms of material and size. It appears to sit about 1cm from the coils that surround the side and back of the unit. It is on the left side of the unit, toward the top/back.

Is this most likely the sensor?

Name:  probe.jpg
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The controls are toward the upper-left.
 
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Old 06-03-15, 05:11 PM
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Could very well be. I was under the impression that the room air entered the lower grille on the front and discharged out the upper grille. If you have a room air filter in the back then that is where the air enters and the probe should be between the air filter and the evaporator coil.
 
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Old 06-03-15, 05:40 PM
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Well I pulled it just outside of the casing.. an inch or two away from original position. We'll see what happens.

UPDATE: No luck. Still shuts off prematurely. Whether it helped at all.. dunno. I'm not sure what else this could be.....Perhaps there is another sensor someplace....

Will be warmer later this week.... It is pretty cool today, so perhaps it did help and am unable to tell..... Still not perfect.
 

Last edited by MSwol; 06-03-15 at 06:05 PM.
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Old 06-05-15, 06:05 PM
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So I'm able to confirm that relocating the sensor a few inches a way (outside the unit) did not fix the issue.

So, there must be a 2nd thermostat that's obscured... or a condition that's causing the thing to shut the compressor off. Doubt there's much else I can do at this point?/
 
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Old 06-05-15, 06:29 PM
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Sometimes there are two sensors...... humidistat and temperature probe for preventing coil freezing.
 
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Old 06-05-15, 07:11 PM
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Interesting.. what purpose does the Humidistat serve?
 
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Old 06-07-15, 03:52 PM
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So after doing some exploratory surgery to no avail, I put the thing back together..

It started doing it's normal BS, but also was rattling.. Figuring I didn't tighten some screws.. or perhaps cracked some plastic in disassembly / reassembly, I gave it a few good whacks still it shut up.

Low and behold, it is now working normally.....
 
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