Central AC Died

A couple of days after I returned from a week-long trip, I realized my house had not yet cooled off, although it had plenty of time to have done so. Before I left, I had set the thermostat to "off" since nothing needed cooling. I put on my HVAC had and started sleuthing. At the service panel, I saw that the breaker had tripped, when I reset it, the AC unit came back on. So far, so good. No? No. There is action but no cooling. Now what?
The AC unit is an older (10 years?) Lennox model in a Squirrel Cage box. I noticed some of the fins were dusty to the point of being partially blocked by Cottonwood tree fuzz, etc. I gave it a good vacuuming and brushing, and made sure no obstructions existed. I haven't yet opened the squirrel cage to check the fan and other things in there, because I have no idea what is Supposed to be in there and what it ought to be doing, except for seeing that there are no obvious obstructions. The wiring & insulation is intact, nothing is kinked, and there is no extra condensation going on anywhere. The blower's filters have been frequently changed (due to extra dust in the air) and the current filter is clean. There are no indications of any water leaks at any point. No extra condensation. No ice, or freezing up. Nor are there any "holes" in the ductwork, or any openings in the metal other than those where the air intakes and registers are located. No other leakages, in other words, so far as I can tell. My home is being remodeled, so all lower level ceilings are open, exposing all the ductwork. No evidence of anything unusual going on. The furnace (thus the fan) are only 4 years old.....
One potential problem is that I think the contractors weren't always as careful about covering the register holes as they could have been....... I have vacuumed a LOT of drywall debris out of those registers/intake openings. I don't see how anything could have gotten to the AC unit, though?
The only odd thing I have seen is that the pressure relief valve on the water heater seems to be dripping. This would otherwise be totally unrelated, but since it occupies the same room as the furnace and air handler, they might be in cahoots, or subject to the same illnesses?
The AC sounds to my ears, as though it is operating now with no strain. Oh - BTW - it has a new dedicated circuit, for which wiring was installed last summer. It worked just fine with the new wiring until this past week, so that probably also is not relevant.
I have run out of ideas. Can anybody suggest some tips for further sleuthing or action? Thanks much! Liz
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Is the outdoor unit running? Can you hear the compressor running, and is the fan blowing air out the top?
--

Christopher A. Young
You can\'t shout down a troll.
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Is your elec meter spinning good when it is running.
Feel the copper lines. Is the big one cool and the little one hot?
On 4 Jul 2006 21:08:32 -0700, "don't quote me, but......"

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Have you pushed the reset button?
JimL wrote:

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don't quote me, but...... wrote:

No heat, no cooling. If no heat, Compressor may not be running. - udarrell
--
Air Conditioning\'s Affordable Path to the "Human Comfort Zone Goal"
http://www.udarrell.com/air-conditioning-total-heat-enthalpy-latent-heat.html
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First things first: shut it down with the thermostat turning the setting hotter, go outside by the air-conditioner unit and have an assistant start the unit by turning the thermostat colder. Does the unit blow air followed by the familiar whine of the compressor?
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