Dometic 8505 with LS300 vents. I had the vents on, as per instructions, when the temperature is below 10c. On the east coast there have been brief periods during the day with the temperature being slightly above 10c, but not many. Fridge not getting cold, though freezer ok. Could feel heat on the top vent and inside, on the fridge carcase. Took the top cover of yesterday and all is well again. Fridge cold and heat gone. These LS300 covers close off about 95% of the vent, leaving just a very small slit at the bottom. I think I shall only use them if it is around freezing, if at all. This is on EHU.