Where is the inverter box in a 1999 prowler trailer?

You did not provide a Model Number so my answer will need to be general.

• Find the 12 volt fuse panel, the converter will be beside it in a void space you will need to remove a screwed on cover or the range to get to. Sometimes the cover is a closet bottom.
• Many times the converter is mounted on the roof or wall of this void space and will be difficult to reach.
• Once you have found it, we often we cut the wires and abandon the old one and install the new one where we can actually check the fuses and such.