Should there be a temperature sensor?
The 2009 heatsink does not have a temperature connection? Is that normal? There is a spot for it on the logic board, but no wire from the heatsink.
The heatsink is incomplete the sensor has been removed, you need another one. The temperature sensor hangs just to the right of the fins on the copper bar.
Please indicate exactly which machine you have as the temperature sensors are different on different models.
If you have a MacBook Core 2 Duo Santa Rosa/Penryn, there is only one temperature sensor.