The temp sensor is under the top cover panel. The whole top will have to come off and it is next to the pump. Make sure it is full of coolant. You have to access the radiator cap under the plate next to start switch. If it is full then it does sound like the temps sensor is going south.
Mike, RVIA & RVSA Certified Master RV Technician
Amy, Dr. Assistant - Roxie & Mei Ling, four legs each
2000 Gulf Stream Scenic Cruiser 450 hp & 1330# torque
06 Saturn Vue, 06 Chevy Z71 4x4 & 2014 Corvette Z51 M7