a/c compressor

The car is a 1998 dodge intrepid 2.7 When the a/c is turned on the compressor clicks on and off non-stop. Took it in to get serviced. They filled it up with freon and cked for leaks. Nothing has changed, it continues to click on and off. Also causes the engine to surge randomly which is dangerous when at a stop light!! What could be causing this? We are about to take it back in again, but wanted more info from the forum first. Thanks!!