A/C not cooling properly

In order for my car to cool i have to put climate in the middle it blows cold i put it on high it blows cold but it feels like the inside of the car is not cooling. My fans runs low but when i put climate on high the fans run high but cuts off and goes back to turning slow and continue the same thing.When i unplug the temperature sensor my fans runs high and doesn't cut off and my A/C blows good and cold on all climate levels and my etc light comes on. I plug temperature sensor back in it goes back to doing what it was doing before.. If any one could help me it would be greatly appreciate it..