To set the temperature differential the system must be Off. Press the ― button and, while holding it, also press and hold the On/Off Mode button for three seconds. Release the On/Off Mode button. Then release the ― button.
there are youtube videos of people doing this as well. i asked my local shop guys about this, and one suggested taking the thermostat off the wall and filling the cavity behind it with great stuff foam and putting the thermostat back on the wall. they say they have had success with this method before on other units... maybe it will help? we are all winterized and put away for the winter but i will definitely be trying this in the spring...
I will post an update as to if this works or not... the clicking is so annoying, not to mention it wakes me up all night long.