One of my rad fans has stopped working...

[Jthoms1]

So how do I differentiate between low and high speed?

I have a 99....both fans operate, fuses are good and relays click. I'm just not confident the low speed is working. Fans come on with the AC, but they are loud. I find it hard to believe it's "low" I'm hearing. Car runs a bit hot...fans kick on and cool her down. I thought it may have been due to the temperature outside but it was cooler today and when I drove it it still get hot and the fans kicked on to cool it down. It usually heats up to just below the 100 hash mark and then the fans kick on. After a ton of reading on this I do know that the gauges are notoriously inaccurate. I just would hate to run the car hot. So is there anyway to if the fans when they're running are either on low or high? It's never overheated, I am between low and high coolant mark on the reservoir and I have the newest .04 blue coolant cap.

Am I worrying about nothing? Install low temp thermostat?