Window AC Unit Performance Declining - Tips?

I have a window AC unit in an upstairs bedroom that is not putting out as much cold air as it once did.
Normally the unit runs all day and night, set at a specific temperature (77 degrees, currently); and the compressor kicks in as needed to maintain that temp. Because the air flow seems a bit lighter and not as cool, I wonder if something might be wrong with the unit, or if perhaps it has 'frozen' and needs to thaw. It's about three stories up, so I can't get a good look at it from the outside, but I see no evidence of ice or dripping.
In case this is the problem, I have turned it off for the day.
Anyone else have any tips?
Thanks!
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I should note, the unit is probably 2-3 years old, at the most. Sorry for the omission in my original post.
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Squanklin wrote:

Quote: "Because the air flow seems a bit lighter and not
as cool"
Check for lint clogged filter; if no filter .. . The blower wheel blades and evaporator fins maybe lint and dirt clogged!
- udarrell - Darrell
--
Factors in the Correct Sizing of Residential Air Conditioning Systems -
Recommended Procedures for Proper Duct Sizing of Residential Air Conditioning
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This is Turtle.
edwin and other have stated evaperator coil dirty and filter but when someone says they have a window unit that just seem like it just don't do as good of a job like it use to. a lot of the time it will be a plugged up condenser coil on the back and plugged up on the inside of the coil where you can't see it.
so here is a small check list to try to see about it.
Dirty condenser in back. Dirty evaperaor coil in front. dirty filter. 100% RH day and high Moisture content in your house. unit low on freon. Outdoor temps going over 100F+ which will slow some brands of units down. Compressor Going in-efficent or not pumping good enough.
Most all window units still under warranty for low on freon and in-efficent compressors for 5 years.
TURTLE
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One more thing: IF there are oil cups on the fan motors, is it oiled each season at least, more often if used more than about 4 months/year? Drying bearings will slow the fans and make them work harder.
He's right about the 5 year compressor warranties; worth checking if all else fails.
Pop
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All of this is good advice,if all else fails the unit probably has lost it's charge of freon through a tiny hole in the unit. Pop Wrote: > "TURTLE" snipped-for-privacy@bellsouth.net wrote in message

--
MarkyMark

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You won't see anything from outside.
If it did freeze, that is the inside coil and may be visible if you take off the front cover. Is the filter clean? Did dust or list get past the filter and clog the coil? It must be cleaned very carefully so they are not bent.
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If the unit has frozen, it won't be visible from the outside.
If the unit has frozen, ice will probably be visible on the coils/fins on the front of the unit once you pull off the front panel and look underneath the foam filter. The foam filter may be frozen to the fins, so, be careful not to tear it.
If you don't see any evidence of dripping (presuming high humidity), you may have a much more serious problem with it. But rule out plugged filters (soak/wring/hang dry the foam filter)/freezing up first.
--
Chris Lewis, Una confibula non set est
It\'s not just anyone who gets a Starship Cruiser class named after them.
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