Clogged evaporator coil?

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Old 08-26-07, 05:00 PM
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Clogged evaporator coil?

Hello, and thanks for taking the time to help me.

My portable 10,000 btu air conditioner has an unusual problem:

The evaporator coil has only one small section which is cold, and the rest is room temp.

Why would only 10% of the coils be cold? If the condenser coil is clogged so close to the expansion valve, I'm surprised it's so cold, given the smaller volume in which the refrigerant can expand. I can't see if the cold portion of the coil is in fact the part nearest the expansion valve but that's my guess, given that it's cold and the rest is not.

I tried to look more closely at this unit, but it clearly is not designed for maintance, as it was too difficult to remove the apparatus entirely from the enclosure. It may even be the circuitry, as the cycle doesn't sound the same anymore. Just fan & compressor constantly working, and register temp like 5deg below ambient.

If it helps, the mfg/model is EverStar/MPK-10CR and the User's Guide is here:

http://www.supportuscenter.com/documents/MPK_Manual.pdf

I've had this unit for a little over the year, and it may be covered by warranty, but I'm not sure if I can find my receipt. Before going through that ordeal, I thought I'd ask you fine folks.
:-)

Any Ideas?

Thanks,

Matt
 
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Old 08-26-07, 09:14 PM
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Only some coils cold

It sounds like you either have a malfunctioning expansion valve, have lost a significant amount of the charge or the compressor is not compressing as it should. In any case, the refrigerant containing part of the unit is at fault & would require the services of an EPA certified tech. I hope you can find the recp't.
 
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Old 08-28-07, 06:53 PM
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Hi Grady,

Thanks for your prompt reply. I too hope I can recover the receipt, as this unit cost me 400-500 bucks just last year!

Assuming no corrosion in the lines (no clogging), and with knowledge that this is a closed system (as are all refridge systems), is it safe to say that the only way part of the evaporator coil could exhibit this kind of temp gradient is if they are pinched shut somewhere?

Thanks Again,

Matt
 
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Old 08-28-07, 07:26 PM
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Other Possibilities

The expansion valve could be malfunctioning (if equipped with an expansion valve), you could be short on refrigerant due to a leak somewhere, or the compressor is not compressing as it should. These or a piece of solder or other debris clogging things up.
 
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Old 08-29-07, 03:09 PM
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Come to think of it.

Come to think of it, the condenser coil is not nearly as hot as it should be, and the exhaust is not taking as much heat away with it as it used to.
 
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Old 08-29-07, 05:48 PM
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I'd put my money on the fact that you have a restriction at the metering device. Wheter it's a capillary or an expansion valve it sounds like it's clogged.

Whatever small amount of refrigerant that is still squeezing by the restriction will boil off and absorb heat, but once it does so the rest of the evaporator is left starved, exhibiting symptoms of an undercharge. Your compressor and condenser aren't ejecting any heat because ther's no heat being transfered from the conditioned space.

In my opinion, when you have a problem with the refrigerant circuit on a $500 dollar unit, you have two options.

Find that receipt, or obtain a SERIEL # from the unit, then call the manfacturer or whomever sold you the thing and see about replacing the unit.
 
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Old 09-01-07, 02:30 PM
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Many Thanks

Hey Guys,

Thanks for answering my questions so thoroughly.

I've since replaced that portable silliness with a 18,000 BTU window unit; should have installed this to begin with. I still can't get the basement < 75deg @ 50% RH (down from 80deg @ 70% RH), but me thinks that's an insulation issue.

At least it's air conditioned now, and hence looking for a receipt for the portable will be boring, but not physically uncomfortable.
:-)

Best,

matt
 
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