There Isapower Outage; You Get A System E Rror Message - Carrier Comfort Non-Programmable Owner's Manual

There
i s 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.