Agree on likeliness of condenser being culprit, but before shelling out cash, get it pressure tested at a ac garage. They'll use nitrogen which will hiss like a made thing if the holes big, and uv dye which helps spot small holes.
I have had two ac failures in recent years, one fiat, one Alfa, both had holed evaporators! Poor design and corrosion caused both. They are £600+ to fix. Condensor is £200 ish fitted. Also possible the fill valves are leaking, common if the caps aren't on? A friend with a vauxhall had problem with a cracked ac metal pipe after his car was serviced as a monkey boy had whacked a pipe while doing a cam belt and 'didn't notice the hissing noise' so so many possible fail points an expert is worth the cash before replacing bits by guessing!
2005 Focus C-Max 1.8 Petrol Ghia + Sony 6 disc, 2007 tail lights, Led bulbs all over and HID front fogs.