Ford Truck Enthusiasts Forums - good source for comprehensive trouble shooting info?

I hate to ask anyone to recreate this info here in the forum. I'm sure it exists somewhere; I just haven't found it yet. Maybe y'all can point me to a good source.

My 06 F450's AC loses freon. Two years ago, I could put a can in, and it'd stay cool most of the summer. Last year, that only lasted a few weeks. Now, I've not added any in a long time, nor used the AC, and summer is coming around so I need to fix it for good. I'm trying to figure our where the leak(s) could be. I don't see any obvious residue at the dryer or lines to the condenser. Haven't crawled underneath to look at the compressor, and not sure what I could tell by looking; it's pretty dirty down there.

I read of O-rings, an orifice tube, accumulators, evaporators, dryer, etc. but I'm not sure where those components are located on the 6.0 engine. From pics I've seen, I think the orifice tube inserts in a line right next to the dryer. I have the special tool to open that line. If there's no trick to fishing it out, I gather that I'm supposed to check its screen for metal or blockage. I guess I'll buy a new one first to compare the old one to.

And I think I've read that the dryer should be replaced whenever the system leaks. Not sure the proper sequence for doing that - I assume I try to find other leaks first, and once they're fixed, replace the dryer and recharge?

If there was a great troubleshooting/diagnostic/service bulletin article/website on fixing Super Duty A/Cs I'd love to read it.

I read of people using leak-spotter dyes, and others cursing them, and others saying they don't find small leaks with the new gasses. I've read of sniffers that don't sniff that well.

Is there a list somewhere of all the likely leak sports for our trucks? Maybe it's more cost effective to just replace some parts than to try to determine which ones are leaking? Although I'm thinking the hoses going to the compressor are a pain to replace, the condenser, dryer and upper lines look easy to access.

I rented a vacuum pump from the auto parts store and hooked it up according to directions. It seemed to work in that the gauge pegged at zero after a little while pumping. It wouldn't hold though. Leaked in air back to where it started within a few minutes. Is that pump supposed to remove all of the freon as well? If so, where does it go? I saw a small pool of oil/water/? next to the pump exhaust like it maybe sucked out of my system, but it wasn't but a couple of ounces. If that isn't from my system, or if there's prolly a lot more left in it (the pump is only sucking air, not gas/oil?), how do I get the rest out so I can fill with a measured amount?

Again, I understand these are lots of questions, and that I'd prolly have more questions once I heard these answered. I know nothing about AC and electrical stuff, and it's all confusing. I hate taking a car to the shop when I don't know what's wrong with it - it's an invitation to get ripped off. If there's a comprehensive source, I don't mind doing the homework, Or if you want to walk me through the diagnosis, I would be very grateful for any help offered. I have to drive to CA from TX next week and need AC.