[RickandJanice]

Sounds like you are drawing enough current betweeen the fan and the lights that you converter is coming on as soon as you flip the switch. This could also be a symptom of a low voltage problem with the battery. You might want to check the water level in the battery. If all cells are full level, then check the specific gravity in each cell to make sure you do not have a bad battery cell. If the battery is good, then you may be just pulling enough current that the converter is kicking in as soon as you filp the switch.

As for the wiring issue, Sounds like you either have short between the wires or something wired wrong. If the light switch and fan switch are on the same wall panel, you might try pulling the switches out of the wall and checking the wiring to make sure nothing is crossed or shorted at that point. Good luck!