The AC gets cold on the highway(not very cold) but in town its up and down. It will go cold then hot then cold then hot constantly. Could this be a loose belt? And when I say not very cold I mean not very. Last summer it was very cold. Now it just gets cool.
Check to make sure the belt is tight. Also, it could be getting low on freon. Have that checked. Finally, there are many other issues that can cause this. The most common is the cycle switch that engages the compressor for specific lengths of time. If it is kicking on and off due to a bad switch, the temp will change often.