My understanding is that more often than not look for some place near your battery compartment. Mine was under the left side of my refer but I had to pull the drawer from under the right side to get to it. There wasn't any vent slots or such to tip me off.
Try this...turn off all your noise making stuff like the AC, fans, radios and such. turn on all your 12V lights and other 12V stuff. You might be able to hear the converter fan. That worked for me.
Don, Sandee & GSD Zeus. Gardian Wings earned are GSDs Gunny (7/11/15) & Thor (5/5/15)
2006 DSDP 4320, Spartan MM IFS, 2013 CR-V, Blue Ox Avail, SMI AF1, Samsung 197R Refer.