How can I make my side-by-side refrigerator's freezer colder?
Measure Properly
Measuring after the door has been open - even for a minute - isn't a fair test.
Put the thermometer in the middle of the freezer. Leave the doors closed for a while - I suggest at least an hour - to let the system recover.   Then open and read the temperature. You should get close to 0 F (definitely under 10) in the freezer and between 32 and 40 in the refrigerator.
If the unit is installed correctly - indoors in a climate controlled space (60-75 F) and the temperature is out of spec, then:
Contact the Manufacturer
The unit might actually be defective. Let them do the troubleshooting and send a (no charge) on site technician to check it out. The key is &quot;brand new&quot; - a gasket, compressor, thermostat or other problem is the manufacturer's problem. If it breaks after warranty then DIY will try to help.