Carrier Aquazone 50QE900-NPWS Owner's Manual page 12

About Advanced Features & Operation
EMERGENCY HEAT - To turn on Emergency
Heat press in the Fan button. While holding
the Fan button press the Up button for 2 seconds.
The Cool setpoint display will read 'EH'.
eh
73
Press for
Emergency Heat
74
FAN
During Emergency Heat the thermostat will turn
on the fan and the 2nd stage of heat, when there is a
demand for heat, locking out the 1st stage compressor.
Exiting Emergency Heat is the same as entering. During
Emergency Heat only OFF and HEAT are available.
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