Factory A/C in 1967-1972 Darts

YY1 said
Filled to pressures for 134a in my local temp of 95-ish per several charts I found including one here on FxBO.

Vent tube through firewall is not plugged.

It's condensation on the outside of the box.

Thoroughly checked several times to verify.

Outside the box sweats? That is interesting. If it has not been out and apart I think I would pull it out and see what it looks like inside... maybe full of leafs or something and blocked airflow.