The aux fan for the a/c circuit has nothing to do with the sensor on the engine. It is not temp sensed, it is pressure sensed [ high side freon pressure]
It is located in the high side line near the drier/reciever. Jumper these will run low fan when a/c is on.
The high speed aux fan is temp sensed and is a thermistor circuit. When the sensor gets to the proper resistance [ temp], it triggers the relay circuit for high speed fan. These two fan operations are independent of one another.