Car AC Working Intermittently?

I sent my car to the Goodyear service center because my AC has been a hit or miss when it's on. Here is the symptoms, during the early morning time, when the outside temperature is cooler, the AC blows cold air continuously. In the afternoon, on my way home from work, the temperature has risen above 80, in Georgia, it will blow cold for about 5 minutes and then it blows warm air. I'll shut it off for about 5 minutes, then it will blow cold again for another 3-5 minutes and then back to warm.

The techs at good year claim I need a new compressor and drier. Even though that may be correct, I have a feeling that's not the issue.

Could it be a pressure or temperature sensor going bad? If the compresser was bad, wouldn't it not blow cold at all? The fact that it blows cold during cooler temperatures makes me reluctant to change the compressor.