Glycol Pump Issue

[Bar Build]

I have a Micromatic Glycol pump, Model MMPP4300-SF, 1/3 hp. The glycol bath froze about a month ago and burned out the agitator and recirculating pump. I replaced the pump and it seemed to work for a bit. Now, I am getting an error message of "AL" alternating with the temperature in Fahrenheit. I discovered the issue when I went to pour a beer and nothing came out. I suspect the beer is frozen in the lines and have shut the system down. Does anyone know what this error message means? Bad thermostat probe or thermostat?

Thanks for any help.