It is a vent! If you have cabinets against the rear wall overhead, look closely inside the cabinets in the center-front of the cabinets. There is a opening in the overhead with a wire loom that comes out of the overhead down into the cabinets. You may gain access to the vent opening through this wire way.
Sid, Lois & HRH MISSY Terrible 3s SHIH TZU
2011 ROCKWOOD 8285 WS
2014 F-250 KING RANCH PS 6.7L/SWD/6R140/BFT
TST Truck System Technologies TM-507SE
DAYS CAMPED 2018 60 DAYS