Hi, thanks for the reply. It makes sense. I am not familiar with cooling/ac systems. The sensor you are talking about is it the water temp gauge sensor that is right next to the fan switch that also on the thermostat housing? Can I use a voltmeter to test if the sensor is bad? If yes how?

Lastly, just for the knowledge sake if the auxiliary fan is running that means the auxiliary switch itself is ok and vice versa right?

Thank for helping me learning AC/Cooling systems now.

Rick