Thanks for the input. I'm well versed on charging A/C systems. I just wasn't sure how to check the compressor for operation. But it sounds like it will automatically start when pressures are correct. The old units in some cases had to be jumped to charge if empty, or low enough to open the low pressure switch until presures came up to allow the low pressure switch to close. When you pulled a vacuum you could sometimes get enough freon in to do that but not always. Thanks for the info I will keep you posted on what I find. I'm not going to get to it for awhile I have a busy few weeks.