The heater blower fan is required for a car heating system to blow either cold or hot air through the fan grills inside your car, if this is not working, you car's heating system is useless. If it is no longer working, the solutions to fix, troubleshoot and solve the problems that are related to it are listed below:
1)The first thing you should check if the fuse that protects the heater circuit is missing or blow, due to a short circuit. See you car's user manual for a accurate guidance on were the fuse is located in your car.
2)To identify if the car fan blower is the problem, locate it were it is inside your car. Once you have found it, get 2 wires and attach them to the positive and negative terminals found on the motor and then attach them to the car's battery, matching the correct polarity. If the fan motor spins really fast and you can feel air being forced out of the heater grills, the motor is not faulty and will not need replacing. If the car heater blower is not spinning, the motor is faulty, so to get the car's heater system to work again, you will need to replace it. If you are short of cash, buy a used one, instead of a brand new one because at the end of the day it does the same job for less.
3)If the car heater blower fan in your car is working, when you connect to the car battery to test it, the first thing you should check the switch that controls the heater blower fan, which is found in your car's dashboard. This switch controls the power the car heater blower fan and activates the motor, if it's damaged, the fan will simply not function.
4)If the switch that controls the heater blower fan is not faulty because you have checked it, then replace or get the heater resistor pack repaired, only if the car heater blower blows out air only on some heater settings. For example: the heater only works on setting 3 and doesn't work on setting 4.