... the fan would not come on at all unless you tapped the heater fan realy that is under the hood. We replaced the realy but it is still not working. Any ideas of what might be wrong and how to fix it? Thanks.

l also asked this in maintenance and repairs because l ws not sure what category would be best.

The heater switch has a plastic pin that it pivots on and is usually the culprit.You will need to replace the switch.Switch can be had at a wrecking yard or just buy a new one.

If the relay is close to the fan motor you may have been jarring the motor as well. when the brushes in the motor wear out sometime if you rap it alittle it will start to run for a while again. Check and see if voltage is getting to the motor. If so it is most likely a bad blower motor.

my money is on it being a bad blower motor.