No air comes out upper air outlets when A/C is.

No air comes out upper air outlets when a/c is turned on. The cold air comes out the heater floor vents. Prior to this occurring, on several occasions I heard a clicking noise under the dash. I first thought it was a/c compressor noise but I now think that it must have been a relay that diverts the airflow between the upper and lower vents.

If it is a relay, where is it located?