If I remember right it does not need to be in auto mode and it will adjust the settings as needed upon remote starting...

Remote start and DATC (Dual Automatic Climate Control)...

For cold ambient air temperatures as determined by the HVAC module AUTO mode to request heat:

-the airflow mode is set to FLOOR/DEFROST.
-the temperature is set to 22°C (72°F).
-the blower speed is set to AUTO.
-the air inlet mode is set to AUTO.
-the auxiliary electric heater is enabled if needed (diesel engines only) (if equipped).

For moderate ambient air temperatures as determined by the HVAC module AUTO mode to request heat or cooling:

-the airflow mode is set to the AUTO.
-the temperature is set to the last user setting (Temperature setting is limited to 18°C (65°F) minimum and 29°C (85°F) maximum. If the temperature is set above or below that range, it will use the minimum or maximum value.).
-the blower speed is set to the AUTO.
-the air inlet mode is set to AUTO.
-the auxiliary electric heater is enabled if needed (diesel engines only) (if equipped).

For warm ambient air temperatures as determined by the HVAC module AUTO mode to request cooling:

-the airflow mode is set to AUTO.
-the temperature is set to 22°C (72°F).
-the blower speed is set to AUTO.
-the air inlet mode is set to AUTO.
-the auxiliary electric heater is not enabled (diesel engines only) (if equipped).