My daily driver car is a 2006 Honda Civic that's bone stock and just hit over 270k miles on the original engine/transmission. It has a small leak in the ac unit to where I have to top it off every year or every other year. I tried the cheap cans from your local auto parts store and they worked for a day or so and that was it. I've heard that you need a high pressure unit to force the freon/product into the lines, and most of the time what you buy from the auto parts stores don't come with that. I'd recommend a dealer or other tech looking at it, as you don't just run out of freon considering it's a closed system. You've got to have a leak somewhere, if that's the main culprit itself and is the reason why you're not getting the cold air.