Last year or the year before I bought a can of AC recharge stuff at Walmart, the can came with the gauge and hose, (you only need to buy the gauge and hose thing once) I unscrewed the blue cap under the center of the dash near your right foot toes when you are driving. I ended up putting 2 cans of recharge stuff in and had great AC again, last week I did the same thing again, but only had to use one can.
I bought several can in the clearance isle last winter.
The instructions say wear eye protection, long sleeves and gloves, I did, I didn't have any problems and watched a few you tube vids before I did it the first time. wear eye protection incase you screw up, you don't want a frozen eyeball.
The gauge gets set to the outside temp and you keep shaking the can an tilting it like the instructions say, it has you let off the button that squirts the stuff in several times to check how much you putting in, DON'T over fill.