I'll just inject this here for grins.
I changed my radiator in 2010, which included removing hoses to the condenser.
After reassembly, I put it all back together and charged it with new refrigerant. It worked fine for a couple of weeks, but lost pressure. It turned out that the O-rings on the receiver/dryer had flattened in the 10 years of being sandwiched in there, and I was able to replace the O-rings that had been disturbed, and the system held its charge with no recharging needed for 5 years until I had to pull the engine 2 months ago. It was able to put out 33 degree air before the engine change and still does now.
I'm kind of thinking that the system lost pressure due to O ring leaks. In my case, the problem was easy to find, using a leak detector. I could also see an oil film developing around the receiver/dryer manifold connection, when mine leaked out.
This time around, it was all new O-rings, since I had to change both manifold pipes from the compressor and the expansion valve, as well as the receiver/dryer.
You can rent gauges and vacuum pump from Autozone now. As long as you have around $300 to cover the cost if you decide to keep the stuff, you need to pay that up front and then get a full refund upon returning it.