I have a Garmin on my bass boat, and when I select the ClearVu option the screen is just black. I've looked at the settings and they all are in default or medium position. I've searched online and all I can find is that it may be a bad electrical connection. The traditional view works fine. Anyone have experience with a problem like this?

What transducer do you have? The ClearV feature is available with Garmin CV and GT transducers.

Had it been working correctly or is this a new boat or installation and it's never worked correctly?

I bought the boat/Garmin used last April and it worked correctly over the summer. This spring I noticed it wasn't working. I'll have to check the transducer when I get home and report back.

Garmins ClearVU, Humminbird Down Imaging, and Lowrance's DownScan, are all similar in technology. They utilize dual frequency transducers for each.
Sounds like you have had a transducer fail or something has happened to your cable/ connector.
Typically if it's a cable or connector issue your unit will give you a fault message saying something like " no transducer detected " when you select the correct frequency range.
It you are getting a black screen and no fault message that usually indicates that your problem is probably your transducer itself.
That would be my first thought. Even though you have gone to default settings you may need to go into your menu. Then to transducers/ frequencies and manually select the freq. for your ClearVU. Hummingbird operates that way I know.