Here is the installation manual. I am not sure if it is exactly the model you have. There is no mention of auxiliary heat being displayed during the defrost cycle.

Here is a link that might be useful: Honeywell Visionpro IAQ thermostat

I looked at the link you gave, and at all the manuals I had, and indeed there is no mention of this. I presume then the heat pump communicates directly with the air handler to turn on auxiliary heat through a "back channel" so to speak, and the thermostat is unaware of this or does not care.

Richard, you are correct. The heat pump controls auxiliary heat signal to indoor air handler. When the thermostat calls for aux heat, then it will display on the screen itself.

This post was edited by ryanhughes on Sat, Mar 16, 13 at 11:53

Mine does not show when the unit is in defrost but I plan to use some spare thermostat wires and send a signal up to some leds behind the stat that will signal defrost mode and aux mode and cast light behind the stat.

It is rarely in defrost unless we are having some sort of moisture event close to or below freezing which is why demand defrost is awesome.

I have a carrier heat pump with a carrier oil furnace for Aux Heat... a Carrier Edge Thermostat.

When HP is in defrost mode, the thermostat shows "Aux Heat" as heating mode.