So the unit was installed 12 years ago. Outside is a Goodman gax160361fc. The fins are all clean. I replaced the capacitor a while back and the unit worked fine for a bit.
I called an HVAC guy and he said it just needed recharged. So he did and it worked great for a few months. Now it's not cold anymore.

I'm assuming there's a leak somewhere. Is there any way for me to isolate it myself?

Also how much airflow should I be allowing? I have one large return in my living room and that's basically it. The handler is on the other side of the wall and that area is sealed off so it only takes in air through the grate in the living room. Is that a no no?

I think it's called a suction line? Is not cold to the touch which I heard means low freon or refrigerant. Whatever it's supposed to be called.

I feel like my info I'm providing is useless lol