Finnex HC-81M temperature controller making a high pitch ringing noise periodically?

[djryan2000]

I have it plugged into an aqueon heater. It periodically makes a high pitch sound like the one when you push the buttons for adjusting the high and low alarm. Then it goes away. It’s still keeping my tank in the acceptable range though. Any ideas?

 

[blaxsun]

Is it a continuous heating alarm?