What was found
CABIN ALTITUDE, ANNUNCIATOR. AT 12,000 FEET WE GOT A CABIN ALTITUDE LIGHT AND A CABIN ALTITUDE INDICATION OF 10,000 FEET. WE IMMEDIATELY STOPPED THE CLIMB. WE DESCENDED TO 10,000 FEET AT 10,000 FEET. THE CABIN ALTITUDE LIGHT EXTINGUISHED AND WAS SHOWING A CABIN ALTITUDE OF 5000 FEET. DURING THE CLIMB, WE DID NOT EXPERIENCE ANY PHYSIOLOGICAL CHANGES IN OUR EARS ON THE DESCENT FROM 12,000 TO 10,000 I FELT UP POPPING IN MY EARS WHEN WE GOT TO THE CABIN ALTITUDE OF 5000 FEET. AT 5000FT CABIN ALTITUDE READ SEA LEVEL. CORRECTIVE ACTION: REPLACED CABIN AIR CONTROLLER. OPS CHECK GOOD. IAW CE560 AMM 21-30-00.