You need to have the Climate Control computer scanned and the basic Air Conditioning System evaluated for proper operation. This vehicle has computerized climate control. There should be some codes that will pin point the what the problem is. The clicking could be a blend door motor and gear set malfunctioning when they get really warm. This should be indicated in the trouble codes as well. Also if your Compressor is not working correctly or your system is not working properly, the data stream from the computer will show weak system pressures.