So if his system capacity is 30 ounces, and he thinks he is low, how many ounces do you suggest he add? How many ounces does he currently have?
A vehicle a/c has a lot of connections with orings. Orings leak overtime, it is just that way. The more they leak, the less vacuum there is in the system, allowing even more leaking. Since the a/c system needs vacuum and refrigerant to work, adding more refrigerant and reducing the vacuum is not going to work for long. An oring in a vacuum holds a tighter seal, so getting the vacuum back up will get them sealed up.

When the OP stated that he evacuated his gauges and got stinking stuff all over himself, he did open the system.

 

The truck is 14 years old and spent most of it's life in southern Florida so I know the A/C was used constantly. And from the PO (who was the first owner) I know the A/C system was never serviced, charged, etc. I'm just going to play it safe and put a vacuum on it to do a system health check and if the vacuum holds for 30 minutes I'll throw 30 oz. in it and call it done.

Now I just need to find the time to do it. Was going to these past two days but my wife had other ideas for my free time.

 

I would suggest slowly adding refrigerant until it starts blowing cold and the compressor doesn't cycle much, and that's usually "good enough." I agree that starting fresh and adding the exact amount is the best way to do it though.

This is a load of nonsense. The purpose of hooking up a vacuum pump is to remove air and moisture from the system, and that's it. If you open the system up, you now have ambient air and moisture in the system. You don't want that; you want absolutely nothing but refrigerant in there. So you hook up a vacuum pump to remove the air and moisture. At this point, you have a vacuum. The dictionary defines the word "vacuum" as: "a space entirely devoid of matter." So when you're done vacuuming, you now have nothing in the system. No air, no moisture, no refrigerant, absolutely NOTHING in there. As soon as you start adding refrigerant, there's no longer a vacuum in the system. You no longer have a space "devoid of matter" because there's refrigerant in it, and refrigerant is matter. What you DO have at this point, is a system that has nothing but refrigerant in it, which is good, and is what the purpose of vacuuming the system is. An AC system does not "use vacuum" while operating. All it needs is a sufficient amount of refrigerant under pressure, with no air or anything else mixed with it. The O-rings are not working in a vacuum, they're holding back 400+ psi of refrigerant. How can you have a vacuum in the system, which brings the pressure BELOW atmospheric pressure, and have a system with 60+ psi (which is HIGHER than atmospheric) of refrigerant in it at the same time? That doesn't make any sense.

I must've missed this part. If he did open up the system, then yes, he should vacuum it first before charging.

 

One thing I've noticed is that my vent temp is uber cold. I mean, it's getting down to about 33*-34* F. Is that too cold even when the ambient temp outside is 74* F? Doesn't low refrigerant cause the evaporator to ice up or something like that?