Have you seen the big fan working? Both fans should spin with the A/C on. If only the small one is spinning, the big one is dead. The big one is important to keep the engine cool, so I would get that seen to sharpish now that summer has finally arrived.
If the AC pump is working, there is normally an increase in idle speed when set to LO to counter the increased load. Does that happen in yours?
Condensers can and do fail. If they don't crack from stones, they fill up with debris, being the first radiator in the stack. Did the regasser use some dye to trace for leaks?