If the LG Gram is plugged in, the fan will always run in sleep mode. Reason - LG have defaulted the BIOS fan control to 'ON'.
You can check it by entering BIOS on your Gram and then enter secret advanced BIOS - Hold Ctrl + Shift + Alt and then press F7.
Arrow over to Advanced Settings and you will see Fan Control = On. Highlighting it shows that the Fan is always on when connected to AC Power. Just change it to automatic and F10 to save and exit. I tried it on my 16Z90Q and then put it to sleep. After a minute or two, once the system cools down the fan completely stop. This works if you are in Sleep Mode whilst on AC Power. If on battery - not sure about that one. Hope it helps!
