I have thermostat ATP32U03/4, and when I go into the settings I can't seem to change the differential settings. For that matter, the differential settings doesn't even show up in my menu. Is there a way I can get into the 'installer menu' so that I can enable and change the differential settings???? Or is this even possible with this thermostat? My unit seems to run in stage 1 for about 5 minutes and then it runs the majority of the time in stage two. By the way, its a Climatemaster TT27 with 4 ton vertical closed loop wells.