ASA Glamis wrote:
The black wires have a a clip that is connected to the fins in the fridge. Any place that is grounded will work as the ground is the same anyplace.
“Wire the blower by grounding it to the fridge internal light. Do not ground the blower to the cooling fins, this will result in corrosion of the cooling unit and premature failure.” - ARP
https://www.arprv.com/rv-fix-fridge-circulation-fan.php#about Given the very low current of the two blowers (less than 1/10 amp), this corrosion may be limited and/or take a long time to develop.