Just a shot in the dark here but make sure that your unit is set up to display the temp in Celsius and not Fahrenheit. 57 degrees Fahrenheit is about 14 degrees Celsius.
Eric
In the installation manual it indicate sthat the back-up battery is not fully charged until iot reaches 16.2 volts. Does that mean that it will never fully recharge in an airplane with a 14 volt system?
Thanks,
Eric