Guys and gals , first off thank you for the add. I have a 1976 firebird formula 400 it is 95%original. I replace the a/c compressor with a new one also replaced all lines and o-rings then flushed and pulled a vacuum. I charged it with R-12 and it will cool to 58 degrees then the temp goes up. If I shut it off for a second and restart it it will cool and do the same thing. Please let me know what I am missing? And what should the gauges read at full charge?