Okay, I left the hoses hooked up to my cav7-486 over the holidays and what r-12 I had in it mostly leaked out.  I did not have anymore r-12 so I put in Freeze-12.  Running I have a suction pressure of 20 pounds and the box is cycling on and off at 35 degrees.  I have the thermostat set around 1, so I barely have it on.  Sounds good but, when the compressor runs I have frost build up on the suction line and on the side of the compressor.  Do I have enough Freon in it?  Or do I have to much?  Also it is about 40 degrees ambient temp, will that cause it to frost instead of sweat?

12-28-2007  Yep definately had it overcharged.  Problem solved.