cooling fan monitoring

Hello, I would like to put a couple of small lights on my dashboard to monitor when the cooling fans on my car cut in. How can I do this? Wiring them into the connectors for the fans will tell me if they are getting power but not if they are actually spinning. I'm guessing I need a sensor or some such device? Regards, Brandon.

If there are 2 wires in the connector of each fan, wire the lamp across the 2 wires.

The simplest & best air flow sensor is a vane switch - air pushes the vane and closes (or opens) a switch. (Forget current sensing methods - they don't work.) Though other methods can be used to indicate rotation (like photo-interrupters), the vane senses both rotation and airflow (assuming it is set for faster than vehicle speeds). But most simply use electrical - a lamp across the relay or fan. If the fans are not moving air, the temp gauge/alarm will let you know.

Frankly with the poster's climate they are unlikely to turn on unless AC is engaged. We don't get hot enough summers! Lights wired across the motor wires and watch your temperature gauge.

Mind you, I always like adding an N.O. temp switch (eg, what I call klixons, and others call...) rated at say 90 or 100C and attached to the block or head. It switches on a lamp or buzzer. Simple, cheap, independent, not foolproof, but only ~$8.