Have you played with the temperature control any? Turning it to the coldest will most likely engage the AC, turn it to hot during the summer and if the compressor is still on then you might have a problem and even then.
It is actually good for the AC system to be used during the winter otherwise you risk breaking and seizing the seals in the compressor, therefore costing you lots of money to repair. So the ac should be used at least twice a week no matter what the weather, during the winter it will not fog up your windows.
Hope that helps. | 
