2010 Toyota Sienna, driver’s side A/C not cold, but passenger side A/C is cold
How would I go about fixing it? I was thinking of using one of those “A/C Pro” tanks, but is there a different way you’d recommend?
You're probably low on refrigerant, and the only way to fix it is to take it to an a/C professional mechanic. You can do it yourself if you can read guages and you have a reverse scale. You have to pull vacuum, then open a set of manifold gauges. Simply opening a can doesn't work. Air will be introduced into the system, and you won't have a way to judge whether or not it's completely full. They require precise measuring, and if it's off, it could either not work properly, or you could blow up the A/C.
Those so-called "recharge cans" are terrible. They're selling the fiction that AC can be fixed by "filling to the green". Dangerous nonsense. You could wind up doing more damage, especially if the can contains sealer (most of them do) which can plug up your AC system. Modern AC systems are very sensitive both to the level of refrigerant and contamination. If you're not familiar with working on air conditioning, as @jshep91 says take it to a pro.
https://www.youtube.com/watch?v=_IBFLMYZEzI
https://www.youtube.com/watch?v=0HCSsv3uYfM
