Yes! Your engine is getting too hot.
This is probably a safety feature that prevents your AC from damaging the vehicle. When the engine gets hot, a sensor can detect this and disengage the clutch to your AC compressor so that the engine does not burn up.
You should either pull over and give the engine time to cool off, turn the AC off (what the engine would prefer), or cruise at regular speed so the radiator can cool down (difficult to do in stop-and-go traffic).
Another question is, "Why is your engine getting too hot?"
You may need to flush your radiator and > In stop-and-go traffic, or if you just run the A/C too long, the
engine will begin to overheat and the air blowing into the will not be
> cold any more. Checked to see if it needed more refridgerant, and that
> was not the case. I'm thinking it might be the radiator fan or the
> water pumps, but I'm not sure. And I'm not sure how you would check > those.
>
> Any advice?
>