Is my chicken safe in the fridge with the fridge set at its lowest setting?

My flatmate keeps changing the dial on the fridge to 1 (1=warmest, 6=coolest). I left a chicken out yesterday to defrost and changed the dial to 3 but left home and came back only to see it set back to 1 again. I dunno how long it's been on this setting, maybe 12h. Is it still safe to cook it?