The clicking sound is from the compressor clutch at pulley. That is the first sign of it starting to go out. It may do this for 3 months before it becomes a loud clacking sound and then locks up, or it may do this for another year before locking up.
You can have just the compressor clutch replaced. This does need to be done at a shop as a special compressor clutch tool is required for removing and installing the new one, plus you have to know how to shim tit. Typically, it will run around $350-400 parts and labor for your vehicle, depending upon local labor rates. Whereas if you wait until it finally locks up when you will need a new compressor, orific tube and accumulator, it will run $800-850