AIR CONDITIONER/COMPRESSOR HAS FAILED AND THE UNIT IS LEAKING FREON INSIDE THE CAR CABIN WHEN AIR CONDITIONING OR VENTS ARE OPEN. THERE IS ALSO A HISSING SOUND AND EXHAUST COMING FROM THE COMPRESSOR, WHICH WAS PROCEEDED BY A BURNING SMELL WHEN THE UNIT INITIALLY FAILED. AFTER DOING SOME RESEARCH, IT APPEARS THAT THIS IS AN ON-GOING ISSUE FOR PEOPLE WHO OWN THIS PARTICULAR MAKE AND MODEL OF CAR - THERE ARE DOZENS OF PEOPLE DOCUMENTING THIS ISSUE ONLINE, BUT GMC REFUSES TO ACKNOWLEDGE THAT THERE IS A PROBLEM. WE CONTACTED THE DEALER AND WERE INFORMED THAT NOT ONLY WOULD WE HAVE TO PAY FOR THE EXPLORATION OF THE PROBLEM, WHICH RESULTS IN THE COSTLY REMOVAL OF THE DASHBOARD, WE WOULD ALSO NEED TO PAY TO FIX IT EVEN THOUGH THERE IS LESS THAN 40,000 MILES ON THE CAR AND IT IS BARELY 2 YEARS OLD. WE HAVE HAD TO SHUT THE VENTS AND FORGO USING THE VENTILATION WHEN DRIVING BECAUSE THE LEAKING FREON CAUSES PASSENGERS TO BECOME LIGHT-HEADED AND DEVELOP A HEADACHE. WHEN THE WEATHER IS HOT, YOU NEARLY SUFFER FROM HEAT EXHAUSTION WHILE DRIVING. ADDITIONALLY, THE HEATING HAS ALSO FAILED AT THIS POINT, RENDERING THE SYSTEM USELESS. *JS