Good people of the forum, I have an AC leak and it seems to be the evaporator. First some questions, then some details.

How can I be sure its the evaporator that is leaking? I used a gas detector, it signals positive in the ac vents.
What am I getting into removing the dash? I read through tis and Bentley and it all seems doable but...sometimes they over simplify I feel like.

I also may have a leak at the ports, possibly. The detector reads positive at the high and low ports / valves. This could be residual refrigerant however I did spray, and clean with soapy water (disk soap). These are new OE valves, replaced both high and low.

Here is the detector that I used:
I should say I recently replaced the compressor, condenser, dryer, and all related o-rings. I had the leak prior to that work as well. The system will hold a vacuum. But not a charge. It holds for 2 weeks or so

All feedback much appreciated. Really want to be sure I'm think of this right before I pull the dash

 

Mini update: I started watching YouTube vids on AC leak repairs last night...

purchased some small water balloons, for testing leaks at the valve / ports

also found a tool to tighten them up if leaking

apparently the gas detection devices can give false positives...

a Super sonic detection device is superior, according to YouTube, but expensive.

going to try autozone for a rental

 

Really scared to remove the dash...anyone have any words of encouragement?