Thats why my post said DRY nitrogen.....
Tinkerboater is right about the filter/dryer too.....the smallest amount of moisture, will at best shorten the life of the compressor and worst will freeze in the expantion device causing a no A/C condition, and drive you crazy!!!!! 'cuz then it will melt, and you'll have A/C then it will freeze, then it will melt, then it will freeze, then it will........ you get the picture? .....
Hey Tinker how's biz up there?

For being in business 2 months I am busy. And loving every minute of it.

Lapse is right! 30'' of vac. for at least 30 minutes to check for a leak. No need to worry about moisture when checking the evap. The moisture will be removed when you pull a vac. on the system before charging!

Thanks all, I know some about ammonia refrigeration (large scale) but next to nothing about this little stuff. I did forget about the dryer, it has one, do I need to replace it (not easy anymore) or can I just add another one in the suction line?

YOU must replace it -- A vacume pump can not remove moisture from a desicant filter drier. If You don't change it it may come apart on the inside and spread the little desicant balls all over your just rebuilt A/C.
And the only way to properly test for leaks is to pump the system up with nitrogen and bubble test it.
Why do you think the factory has a maximum pressure rating on things- because they expect you to pressure test it.

And if it has been open to air and moisture for very long I personally would triple evacuate it. Pump it down for 30 minutes and fill it back up to 0 with nitrogen then pump it down again for 30 minutes and refill it with freon to 0. Pump it down one last time and then fill it with the rated weight and you are good to go.

Tink is right, you MUST replace the drier if it has been exposed to atmosphere for any longer than about 15 minutes, and everything he said after that is also spot on.

Ah crap, thanks for all the advice, I might just have to can the AC for this year. If I take the compressor/ condensor unit out again and have the dryer replaced, how do I get it home and hooked up in less than 15 minutes? I should have just paid to have this done huh.

Unless you have the BARE minimum, a vaccum pump, set of gauges and the rquired refrigerent and the knowlege to use them then yes you will have to pay to have it done.
How were you going to connect the lines together?

I have a friend at the marina who has that stuff and will do the vacuum and freon charge after I am in the water. Im just trying to get it all together before the engien goes in, because the unit is not coming out without the engine out. I removed the unit and will take it somewhere to get the dryer changed. There is a pot on the suction and discharge side.

other side