I want to top off my Expedition AC. It doesn’t cool. Somewhere around 2018 it stopped cooling well and I never took care of it. We basically had it vac and refilled and it holds cold for a couple of years. It’s time to do that again but I want to do it myself. My F150 all original

AC starting doing this and I’ve been topping it off based on temp and pressure charts and it’s been working awesome. It’s a 2002. I am totally and completely aware that this is not the preferred method and vacuuming it out and weighing to refill is. But at 400,000 miles, I don’t care.
The expedition is a TXV system and my F150 is a FOT. My question is, do I need to know or do anything different when reading my gauges on the TXV expedition system or just too off the same way with my gauges and pressure chart? My goal is to get sim cooler temps than 60 degrees. It’s 107 in the shade and kids and wife need it a little cooler.
I buy r134a by the case and am willing to use my yellow jackets for something more than one truck and a dust collection.
