2015 GMC Sierra expansion valve leak at firewall

[Highvol]

I am replacing the condenser in my 2015 Sierra because of the dreaded condenser fail, however during soap testing I also get a slow leak bubble from behind the expansion valve. No leak from the lines going into it, but from behind the block inside the black sleeve that surrounds it. Is this a common issue and do I possibly need a new core? It is such a pain to get to the block/core I am wondering if I should be planing on replacing the core too? Thanks for any assistance with this folks.

[Tim]

Are you saying the foam pad between the valve block and the firewall, tubes running inside the cabin?

[tony1963]

Are you checking this with the system off or on?

The reason that I'm asking is if the system is on and the fan is running, you will get a certain amount of positive pressure at those sealed joints. That positive pressure is what makes the air come out the vents.

Now, if you are getting bubbles with the system at rest, I can only think of pressurized refrigerant that would be the cause.