Converter Failure... again!

The most likely cause is not the converter at all. By failure, if you mean your batteries are not charging, then you need to look at the system with a voltage meter to see what is going on.

My converter was not charging my batteries. My voltage meter on the converter output said 13.6 volts. My batteries were at 12.0 volts. The negative wire from the converter to the battery was loose in the terminal.

Yes, it requires some skills with a meter, but many converters are replaced and the wires tightened, or sometimes not tightened... and the customer gets a ding.

Is it an WFCO? That may be fine if you want to keep giving money to world friendship. The other bad thing is that they are not heavy enough to be boat anchors.

If you want something better maybe try a Progressive Dynamics. Best to check to be sure everything else is ok. Maybe the dealership didn't really replace it.

Need to be sure it is not something else of course. And having another one fail can just be a coincidence if not due to abuse as suggest. Something covering it or blocking the vent area, bad batteries over working it etc.

Some converters are known for short life and early failure.

May I suggest a Progressive Dynamics 9200 series (Or 4600 if the converter is part of the power panel) Mine lasted over 12 years.

Sounds like the dealer done a switch with another old converter

Any modern converter made in the last 10+ years works perfectly fine without a battery.
Have you done any work on the electrical system lately? Touching the battery cables together, even for a second, will blow the reverse polarity fuses.

heat.. space too confining not enough ventilation to the converter

bad batteries constant heavy load, most converters are built to be chargers not power supplies, weak batteries that won't charge or running with No batteries
some converters do not work well as 'power supplies' in a No battery situation

what brand/model converter ?