Here is what happened to me.
Mine was leaking, couldn't find the leak.
I tried the dye, no luck except I kept noticing a bunch of the dye in the cap on the low pressure service port.
I changed the schrader valve in the port (just like what is in a tire stem) and it fixed the leak.
Dealer had previously quoted me over 1k to replace the whole assembly.
So consider that it could be leaking out of where you add the freon...
just my .02
PS a new valve was $8 and the tool to chage it was 5 or 10. The pressure blew the first valve off the tool and I lost it, so I had to buy a second.
...SPEEDING PAST THE LINE OF GOOD TASTE...