My 1973 B body was converted to R134a by the previous owner.
It does a good job of cooling but the evap box under the dash sweats and drips.
It is NOT leaking.
I wonder if a more efficient condenser might help.
Just part of living in a humid climate. There is suppose to be a drip pan in the box to catch the condensation then a way to get it through the firewall. The '73 A bodies had a small tube that was near the passengers feet that took it out through the firewall, the earlier ones the tube was part of the pan and just went through the firewall when you installed the box. Look for that tube (usually about 3/8") and see if it is plugged or maybe it had the transfer tube that is now missing.
The service manual is hard to see but it looks like the Coronet is like the earlier one and it is a direct shot from the back of the box through the firewall. If that is true then it is likely plugged or the catch pan has a rust hole in it.
