What was found
AT CRUISE, FL390, WITH AUTO THROTTLE AND AUTO PILOT ENGAGED, AUTO PILOT DISCONNECT LIGHT SHOWN & AURAL WARNING SOUNDED. PITCH-YAW DISENGAGED. AILERON MOVEMENT RESTRICTED. A-P DISCONNECT BAR USED. NO HELP. USED 15LBS PRESSURE TO DISENGAGE AILERONS. RE-OCCURRED DURING HAND FLY. REQUIRED 6 LB PRESSUSE TO DISENGAGE AILERONS. EMERGENCY DECLARED. DIVERTED TO ORD. *S/D* IT WAS DETERMINED THAT THE ABOVE DISCREPANCY WAS CAUSED BY ICING OF THE AILERON CONTROL CABLES LOCATED IN THE LEFT WHEEL WELL. THE ICING WAS DUE TO THE APPARENT BUILD-UP OF WATER ABOVE THE CANTED BULKHEAD PANEL JUST FORWARD AND ABOVE THE LEFT WHEEL WELL. WATER BUILD-UP WAS ATTRIBUTED TO BLOCKED DRAIN LINES.