Hello,
I don’t know much about electronic circuits and need some help with a project.
I have a ’66 MG Midget and have replaced the belt driven cooling fan with an electric fan. The relay which turns the fan on and off has two separate output wires which are energized when the coolant reaches a preset temperature. The relay is designed to operate a single or twin cooling fan, which is why it has two separate outputs.
I am only using a single fan and would like to use the unused output wire to run an indicator light on my dash so that I can see when the fan is running. Normally, at highway speeds the radiator would receive enough airflow to cool the engine without the fan being energized. I cannot hear the fan run so I would like to monitor its operation via the indicator light.
I hooked up a 12V LED to the unused output wire. In the garage the light works well. When the fan turns on the indicator light is illuminated. When the fan turns off the light goes out. But when driving the car it does not work that way. The light does not go out or it operates sporadically, sometimes not fully illuminated.
I am thinking that when traveling at highway speeds the wind through the radiator is blowing across the fan blades causing them to turn. With no power to the fan motor it begins to act as a generator when it is being turned. My guess is that this creates enough electrical feedback to energize the LED bulb.
Could this be possible, and if so, what can be done to only allow the LED to receive power then the fan is energized? Would a resistor in-line work, or is there some device that would prevent the flow of current until it receives a full 12 volts from the rely?
I will appreciate any advice you can give.
Thanks,
Paul
I don’t know much about electronic circuits and need some help with a project.
I have a ’66 MG Midget and have replaced the belt driven cooling fan with an electric fan. The relay which turns the fan on and off has two separate output wires which are energized when the coolant reaches a preset temperature. The relay is designed to operate a single or twin cooling fan, which is why it has two separate outputs.
I am only using a single fan and would like to use the unused output wire to run an indicator light on my dash so that I can see when the fan is running. Normally, at highway speeds the radiator would receive enough airflow to cool the engine without the fan being energized. I cannot hear the fan run so I would like to monitor its operation via the indicator light.
I hooked up a 12V LED to the unused output wire. In the garage the light works well. When the fan turns on the indicator light is illuminated. When the fan turns off the light goes out. But when driving the car it does not work that way. The light does not go out or it operates sporadically, sometimes not fully illuminated.
I am thinking that when traveling at highway speeds the wind through the radiator is blowing across the fan blades causing them to turn. With no power to the fan motor it begins to act as a generator when it is being turned. My guess is that this creates enough electrical feedback to energize the LED bulb.
Could this be possible, and if so, what can be done to only allow the LED to receive power then the fan is energized? Would a resistor in-line work, or is there some device that would prevent the flow of current until it receives a full 12 volts from the rely?
I will appreciate any advice you can give.
Thanks,
Paul