Carrier Comfort Non-Programmable, Owner'S Manual

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21
What if . . .
There is a power outage
If you lose electricity and have batteries installed, the thermostat will
continue to display the indoor temperature because it has a battery
backup power source. This means that even though your heating and
cooling system doesn’t work, you will still be able to monitor your
home’s temperature.
You get a system error message
Here are the possible system error messages and what they mean:
-- The room air sensor reports that the room air temperature is
above 150° or below -50°.
E4 The memory has failed and the thermostat will return to the
default factory settings. Call your heating and cooling dealer.