I decided to add two fans at the top refer vent. They are thermostatically controlled as well as manual override. 3 amp inline fuse.
It is currently 89F in the shade. The two added fans have turned on to level 3/6 (auto mode). This means fans are turning at half speed. The hotter it gets, the faster the fans will spin. I can feel the warm air exiting the refer vent cover....good sign!
The single OEM fan has yet to turn on. If trailer/refer were in the direct sun, it would have turned on by now (last testing I did).
I'll do some testing over the next several days and see what I find. It's supposed to cool off into the low 70s by Saturday, so testing in the heat may not happen until next summer.
