i too have the same problem but i replaced the low pressure switch and it still does it. my ac blows really cold when it works but when i stop or slow down the compressor clutch disengages then it blows warm then when i start driving again the clutch re engages. is this a compressor problem or a clutch problem when the clutch is engaged the ac blows relay cold. and sometimes it works when im stopped and other days it does not work when im stoped.