They should be able to answer your problem. The comes on but the vent nor heater does followed the wiring diagram sent with the vent but thier calling for a red wire connection.

Nutone Wall Heater Wiring Diagram 1550 Nutone Electric Wall
Nutone 665rp wiring diagram. The wiring diagram calls for a red wire in addition to the white and black that i have. Each wire opening has a release slot. Im trying to install a nutone model 665rp bathroom vent light fan heater unit. Trying to install a nutone model 665rp bathroom vent. Identify your wires and follow the instructions in your manual. Instructions say connect white wire from unit to white blue wire from unit to supply wire for vent.
I have wired the light and the fan together on one switch and the heater to the other switch. If you need to run a new wire from the units location to the switch box or connect it to the heating unit do so now. The only wires coming thru the ceiling from the switch are 2 black 2 white and a cooper wire. Other talk help wiring nutone 665rp heatlightfan i am getting ready to install new nutone 665rp in place of an old one. Nutone 665rp wiring diagram wiring diagram is a simplified good enough pictorial representation of an electrical circuit. 513 527 5173 665rp ii.
The manufacture did not provide us with a parts diagram for the 665rp. Always order by cincinnati oh 45227 1599 current part number phone. 30652 000 89760 grille 89760 000 53740 lens 53740 000 89765 reflector 89765 000 35758 lamp socket 35758 000 nutone attn. I have a double switch with white and black wires grounds 2 white and 2 blacks to feed the unit. Nutone vent fan heater repair replacing the grille and lens nutone part s89852000 duration. Wire opening release slot if the switch has not been wired properly and wires need to be moved.
Parts department 4820 red bank road note. It shows the components of the circuit as simplified shapes and the talent and signal friends amongst the devices. We have manuals guides and of course parts for common 665rp problems. I dont know if there is a thermal overload or some type of circuit overload in this unit. I have only black and white. Operation model 665rp page 4 operation before using heater make sure heater has been properly installed according to installation steps beginning with the preparation section on page 1.
I think if you call nutone technical service at 888 336 6151. Generally you will need to connect the wires of the same color with a wire splice connector sometimes called wire nuts before securing the unit to the ceiling.