Well, mine is temperamental at times.
02 FXS, climate control.
Sometimes it feels the need to cryogenically freeze me out of nowhere,
almost always on already cold days, and the warm-up time for the climate
control feels like forever on a hot day.
Perhaps get it checked by a dealer, doesn't sound like it's out of gas if it
still cools down.
Quite possible the compressor turns off at idle; or the alternator is not
turning fast enough to supply enough power.
Does the engine speed increase when you turn the aircon on? Turn the AC off,
leave your car running for a short while (20-30secs) then turn it back on.
Idle speed should increase slightly to allow the alternator to supply enough