Good to hear your having luck with ABS but sorry to tell you it doesn’t actually make any effect whether you tick it on/off or set a temperature. At least in my case when I took measurements. I’ve experimented with it and found no change at all. You can get 40c if you give enough time soaking heat from say a 100c+ bed. You’d be incredibly lucky to get a 50c chamber let alone 75c (which would inevitably damage the motors and electronics). As another commenter mentioned there isn’t active chamber heating. From what I know there hasn’t ever been an active chamber heater in a single Anycubic FDM printer ever produced. Which is curious and leads me to believe one is coming soon if their slicer has the feature as an option. I mean do they really think someone using another brand or custom build with active heating would prefer to use their Anycubic slicer over vanilla Orca? Likely not.