Maybe your blend doors have failed, in which case you should have air
coming through your defrost vents.  Designed for safety in the event of
failure.  Sometimes it is just a vacuum actuator arm that breaks, or a
vacuum hose falls off.  If it's under warranty take it to the dealer
unless you want to hunt around behind the dash looking for the point of
failure.

Could it be the blower isnt working?

If it's the standard, knob-type speed control type, there's a resistor assy
in the heater housing (under the dash, or under hood in some veh such as
minivans)  This is a flat plate that has several wires connected to it.

This often fails

Sounds like your plenum diverter doors are not functioning. Is the cold
air coming out the defroster nozzles... at the bottom of the
windshield?

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