I did it for the first time on my gs300 and it worked like a charm. You can get a kit at the local autoparts store. Should come with a hose with a guage attached and 2-3 cans of refrigerant. You just find the Low side port ( near the passenger side firewall on the 3.4L) and with the truck off you screw the can to the hose, attached it to the LOW side and puncture the can. Start the truck and run the AC on high till the can is empty. Every time you change the can turn off the truck and start it and run the ac for a min or so to empty the can. With the AC running and the hose attached the guage should be at about 60PSI to be full, but it it doesn't need to be full just within the range (should be marked on the gauge.) Go for it.