Question for AC experts

I have a 98 Ram SS/T with an AC problem. Holds charge for a few days only. I tried the dye method and electronic sniffer but found no leak. I then filled system with Nitrogen (on low side port only) and can't find any leak under the hood. I'm thinking it's an evaporator leak in the dash.
So:
1- Do I need to repeat the last test hooking up Nitrogen tank to both and low side ports?
2- Is there a trick or a method to test the evaporator before tearing into it?
Thanx guys.

If you put dye in the system, you can look for evidence of dye in the water dripping out of the evaporator with the light. I'd do it at night.

You can be pretty darn sure it's the evaporator if you have not found any other leaks. I have replaced several of them in the past.

My sons 95 ram has gone thru 2 evaorators leaking. MY 99 ram 1500. the evaporator leaked. change evaporator bob h 708 687 1187

Evaporators were a common problem in them and Dakotas.If you havent done one look for about 8 to 10 hours.Change the heater core while you have the dash and box out.My buddy thats a Mopar tech can do them in about 3 to 4 hours.Rocky

Thanx guys for your responses. I'll have to tear into it after removing the intake and fixing the famous intake oil consumption problem. Oh well. Better than working on my stupid Mercedes.