AC Not Working Again - 2001 Nissan Sentra SE

I had my air conditioning fixed about 6 or 7 months ago, the garage checked for leaks and said they could not find any but it must be a really small/slow leak so they filled the system and tested for a few hours and said there was no loss in pressure and that it blew ice cold the whole time. The repair took place near the end of the summer/beginning of fall and it was not used often during that time.

Now we’re back into the spring and have already had a few very warm days but Saturday I was driving on the highway and it was quite warm so I decided to turn on the AC but to my surprise it did not really work. I can hear the compressor turn on when I have it set to blow through the dash vents but the air is not cool at all and instead the same temperature as outside. Thinking that maybe it was a result of not being used all winter I left the AC on for a good 20 minutes or so but still nothing.

This morning I called the garage that did the work on it and he’s telling me to make an appointment to bring it in and they would go and check for leaks with the UV light and that it would cost me an additional $100 just to check plus whatever else is needed (which I think is BS).

Any suggestions for what to do, what to look for or if you’re in Canada (GTA preferably), somewhere to take it?

As a side note, as I mentioned, when I have the AC turned on and it’s blowing through the vents on my face I can definitely hear the compressor turn on without a doubt and it stays on. When I turn off the AC when in that setting it’s clearly turning off too. However, what I have also seemed to notice is that if I turn the vents to blow on the front window without the AC turned on it sounds as if it’s already turning on the compressor and if I go and turn on the AC there is no difference in what I’m hearing or feeling.

Any help or thoughts would be greatly appreciated.