Carrier Comfort Non-Programmable, Owner'S Manual

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20
What if . . .
The battery icon is displayed
The battery icon appears on the display only when the battery starts
to lose power. Replace it when one-third of the icon is black. If your
thermostat is battery powered and you wait until the icon is just a
silhouette with no black bars, you will slowly lose thermostat functions
until it doesn’t work at all.
“Aux heat on” is displayed (heat pump systems only)
Aux heat on
is auxiliary heat. It applies only to the heat pump version.
If it is on, you will see
aux heat on
. When it is displayed, it means the
system has determined that it’s too cold outside for your heat pump
to heat the house without help, so it’s getting help from the electric
heaters. This happens automatically.
“Em heat” is displayed (heat pump systems only)
Em heat
is the display term for emergency heat and applies only
to the heat pump version. You have to turn on emergency heat
manually – it doesn’t happen automatically – so if you see
Em
heat
on the display, it means somebody has turned it on.