Why does a Jeep Grand Cherokee's heat vents output cool to mild warm air until the sound of the air in the vents changes from a medium pitch to a low pitch and then output hot air.?

um i think cold air follows warm air

Yes

!. You could have a bad heater core. 2. You could have a blown fuse. 3. Your thermostat could be bad. 4. Your air conditioning could be on.

warm air cools quicker

Your air handler is working but the compressor outside isn't. The air handler is responsible for pumping the cooled air through the vents and into your house. It may be located in the attic,...