To charge the ac in your holds, you will need a set of ac gauges that work with r134 freon. the yellow hose goes to low high or the small connector and the red goes to the high side or the larger port. the high side could not go any higher than 250psi. you put the freon on the low side. you use the hose in the middle of gauges. don't use the freon sets that are sold at autoparts stores. that don't have gauge on high side which can cause problem.
I have answered a few ac problems today and I will tell you the same thing. If you don't know what you are doing you can hurt yourself or worse. The kits sold in stores are in my opinion are bad to use. It gives everyone the feelings they can repair them on their own, and you have to know what you are doing.