A/C Freeze Sensor - How do I check a faulty sensor?

Doug, We don't have the 10 button control system, we have the Firefly multiplexer touch screen. The compressor works for exactly 2 minutes after starting and shuts down, but the fan stays on until the a/c is turned off on the screen. There is a delay of around 2.5 minutes to restart the compressor if you turn it off and on again immediately. The compressor always starts but intermittently turns off after 2 minutes if the sensor is installed, but always turns off if the sensor is not installed.