Thought I'd start a new thread.

I spent about five hours yesterday taking apart and cleaning the a/c
condenser. It didn't help.

When I arrived on scene, the a/c was working fine. Cold air was blowing
out of the vents. The refrigerant drier cannister happens to be located
on the small line outside the evaporator. This line was very slightly
warm to the touch. The larger copper line going into the evaporator was
cold to the touch. The outside of the plenum was also cold (not
freezing).

After about 30 minutes, the a/c unit's fan turned off, the furnace fan
remained on, and the evaporator line outside the plenum, and the plenum,
got warmer.

Time to clean the condenser. I turned off the thermostat, pilled the 40
amp fuse at the a/c unit, and disassembled the side panels, the fan, and
any wiring as necessary. The compressor had an orange vinyl insulated
sort of pull down 'hat' over it. I took that off, too, to get the
compressor specs, if needed, and I put my hand on top of the compressor.
It was hot enough that I couldn't keep my hand on it for more than a
second or so, but not hot enough to cause immediate burns.

There were lots of leaves in the drip pan, but not much came out of the
condenser. I first vacuumed both sides of the entire consenser, and
there was not much debris at all. I then wetted and sprayed foam on the
outside, and rinsed from both the outside and inside, until all runoff
water was clear. Actually, I was surprised at how little dust/dirt there
was. The only thing that was really dirty was the temp sensing unit that
sits on the small copper line, right where it enters the compressor. I
removed it and cleaned it off good.

I got it put back together, turned it on. The outside temp was now 100
degrees. The indoor temp was 77, and I called for 66 at the thermostat.
Cool air started coming out, measured at 64 degrees (I guess the attic
ductwork was really hot) and it ran fine for about 40 minutes. Then,
warm air came out. The a/c fan stopped. I hand checked hand temps at
the plenum, and it was warming up again.

Crap.

I'm calling another company out for a another look before I replace
anyting major.