HVAC fan? Engine cooling fan?
Which fan is not working? Engine fan or HVAC fan?
Assuming you're referring to the HVAC blower, and not the engine fan, it could be a bad relay, the blower motor could be seized or a solenoid burnt out, it could be bad wiring, it could be a problem with the control switch.
fan motor protector
the HVAC fan is under the passenger side dash , unsnap the clips under glove box and it should be right there very easy to get to.
This could be due to a faulty fan motor, a defective capacitor, or a problem with the fan blade. It might also be caused by an issue with the wiring or controls of the unit. It's best to have a professional HVAC technician diagnose and repair the problem.
Blown fuse, bad switch, defective blower motor, or bad HVAC resistor pack. Wet fish caught in fan blades??
Need more info. Engine coolant fan? HVAC fan? What year? What model?
If the HVAC blower motor does not work on any speeds, I would suspect the motor or the switch is bad.
When dealing with HVAC systems, notice that there are two systems at work, and two possibilities for failure: the HVAC control system, and the actual HVAC unit. Determine if your problem is in the function of the controller (blank screen, not turning on, relay does not click on when fan or thermostat is set past current temperature), or in the HVAC unit (thermostat relay is clicking but HVAC fan does not turn on, condenser outside fan is not spinning, etc.) If the air conditioner was 'grounded', as I understand it, I would think your HVAC breaker would trip. This should help you figure out your problem.
The heater fan in inside the HVAC housing behind the glove box. The radiator fan is mounted to the radiator.
Check your outside unit. Is the fan blowing? If not replace outdoor fan motor or the fan capacitor. If the fan is running then the compressor may not be. Usually a quick fix by replacing the capacitor. In most units a dual capacitor that is bad may shut down the fan or compressor. Call a HVAC technician to replace it. This can be very dangerous.