How does the motor operate the fan?
some fans are driven directly via a fan belt to the crank shaft.
Others are electrically driven and are actuated when the engine reaches a certain temperature.
Why will the radiator fan on your 1999 jgc not come on when you start your car but works when you run hot cable direct?
98 Chevy cavalier runs hot in traffic or on interstate fine around town replaced radioator last year did not cure it?
No, the motor manufacturer maintains a specific temperature range for motors to operate in. It is usually 40 degrees C. The frame design and cooling fan on the motor shaft keeps the motor operating at a temperature within the manufactures specifications. This is regardless of whether the motor is single phase or three phase.
The radiator fan sensor switch or the radiator fan motor are at fault (maybe even both). Wire the fan motor direct to see if it will run, if it does, replace the sensor switch. If the fan motor doesn't run, replace the fan motor before you buy a new sensor. If after replacing the fan motor, the fan still doesn't run, then replace the sensor.
Disconnect the fan motor electrical connector. Unbolt the fan bracket and shroud assembly. Take the harness connector from the shroud. Lift the shroud out of the engine compartment. To separate the fan from the motor take loose the motor shaft clip. Remove the bracket from the fan motor by detatching the harness from the retainers then remove the mounting screws.
1. Disconnect the negative battery terminal. 2. Disconnect the fan motor electrical connector. 3. Unbolt the fan bracket and shroud assembly. 4. Lift the shroud out of the engine compartment. 5. To detatch the fan from the motor, remove the motor shaft clip. 6. To remove the bracket from the fan motor, detatch the wiring harness from the retainers, then remove the screws.