I'll assume that you have cleaned you filters and used to canned air to blow out the rest of you notebook, I usually just put a stick in the fan to keep the fan from overspinning then give your system a good blow out.
Well then it appears that you have a hardware failure. the fan speeds are controlled buy the mother board there is no way for us to alter the fan speeds. I would advise you to contact cl-albert he can be very helpful with moving your NB through the repair center successfully .
G752VY-DH72 Win 10 Pro
512 GB M.2 Samsung 960 Pro
1 TB Samsung 850 pro 2.5 format
980m GTX 4 GB
32GB DDR 4 Standard RAM
Z97 PRO WiFi I7 4790K
Windows 10 Pro
Z97 -A
Windows 10 Pro