Hello Dcastro7,
what is the label under the White Wire on your old thermostat?
At this time I see the following:
R - Red Wire is Power In
C - Blue Wire is Power Common
G - Green Wire is Blower Fan
Y - Yellow Wire is Compressor Control
O - Orange Wire is Reversing Valve Control
AUX - Brown Wire is Auxiliary Heat
?E? - White Wire is this Emergency heat?
Unused, Black Wire
There is not normally Auxiliary heat and Emergency heat in the same system.
In a Heat Pump type system, when the heat pump is in heating mode, the outdoor coil will tend to build up frost and ice. This will need the heat pump to activate the defrost cycle. When that happens, the heat pump outdoor controller will activate the auxiliary heat. Usually this is electric heat strips inside the indoor unit. When there is a thermostat with both Emergency and Auxiliary heat, the two conductors are typically wired together in the air handler. This would allow the homeowner to activate the auxiliary heat as Emergency heat in a time when the outdoors unit failed. By doing this it provides some heat until the HVAC service company can arrive and repair the outdoor unit. The only Nest thermostat that can be set up the same way is the Nest Learning Thermostat ie., the 3rd Generation.
The AC Cooling Wizard
Google Pro, Mechanical Engineer, Electrical Engineer and HVAC service company owner.
