What was found
ANTI-ICE DUCT WARNING MESSAGE ON CLIMB OUT. WE HAD WING AND COWL ANTI-ICING ON, AND GREEN ICE MESSAGE. RAN QRH. MESSAGE CLEARED AFTER CLOSING 14TH STAGE. LH FUSELAGE SIDE INDICATED RED. FLT 3891 DLH-ORD WITH 47 PAX. CA WAS FLYING THE A/C AND ENCOUNTERED ICE AT 15K BUT RECEIVED ANTI ICE DUCT WARNING AT 24K. CREW SHUT OFF THE ANTI ICE BUT MESSAGE PERSISTED UNTIL 14TH STAGE WERE SHUT OFF. CREW DECLARED AN EMERGENCY BUT DID NOT INFORM THE PASSENGERS. NO ICING CONDITIONS INTO ORD, TAXI WAS NORMAL, A/C WAS DEPLANED NORMAL. NO RESCUE VEHICLES RESPONDED TO EVENT AND NO DAMAGE TO A/C OR PASSENGERS WERE NOTED. A/C LANDED ON 27R. ***AIRCRAFT REMOVED FROM SERVICE*** T/S PER FIM 36-20-00 SECTION 2 RED ANTI-ICE DUCT WARNING. PERFORMED OPERATIONAL TEST OF ANTI-ICE CONTROL AND INDICATION SYSTEM NORMAL MODE GOOD AT THIS TIME.