I have a 1979 with a 305. I live in South Texas and it has been hot down here. And the humidity makes it worse. Well anyways. I converted my A/C to the new 134a from R12. Whenever I turn on the A/C the temperature goes up. Once it hit almost 250 degrees. I can be on the expressway going 75-80 and the temparature still doesn't go below 210-230. I notice that the compressor is always on. I've seen other cars where the compressor turns on and off. Is my new compressor history / defective or what. Or is there something else that makes the compressor turn on and off. I'm getting sick and tired of this A/C problem. Any ideas what it might be?