2001 Ford Taurus Air Conditioner

Hi All,

I have a 2001 Ford Taurus that I have been very happy with until
recently. A few weeks ago, when it first started to get hot, I turned
on my air conditioner for some relief. The air was nice and cold for a
few minutes, then all the sudden I could tell it was no longer working,
since the air started to get warm and humid. Further investigation
helped me realize that the compressor was not engaging.

Thinking that maybe the compressor was just low on oil I bought a can
of R134 and filled it back up to the safe level. The air conditioner
was blowing nice and cold afterwards, although I only ran it for 10
mins or so in the driveway.

Yesterday I took the car out for a spin on the hottest day of the year
so far (90F or so). The air conditioner was nice and cold for about
10-15 minutes, and then the compressor kicked off yet again and the
cabin heated up to unbearable temps. I stopped in at my local parts
store and the tech there put a gauge on the low side of the system and
confirmed that the A/C pressure was correct. (I believe it was about
35, but I dont remember exactly. It was in the green) Whenever we
tried adding coolant, the pressure would go up a little, and then
settle back down to 35 or so. It seemed impossible to overfill.

On the cooler days, this doesn't seem to happen. Only on the warmer
days have I noticed it. After it shuts off, the only way I can seem to
find that gets it going again is to turn off the car and let it sit for
a bit before it will eventually kick back on.

I'm wondering if anyone has any ideas of where to look. I don't know
if I have a leak, or if some other part is out of whack. It seems
strange to me that it works till it warms up, and then quits. If I had
a leak, I would think it would leak out to the point where the
compressor no longer engages. I know they have sensors in them that
disengage the compressor when the levels get too low.

I'm hoping that I don't have to pay big bucks at a local repair shop to
get this fixed. Since I usually do my own work, I want to make sure I
do my own due diligence first. Thanks for any help in advance.