One thing I'm finding out going through old forums that might be a possibility.
Originally, on some of these old vessels, Hatteras built the Helm area around the air handler after it was installed.
The first person that had to get to the air handler had to make an access port which probably explains why some access ports are through the formica top and some access ports were created through the galley cabinet.
It's possible mine hasn't been gotten into yet which might explain why I don't have an access.