What was found
AT 12,300 FT DESCENDING TO 12,000, ACFT STARTED ON UNCOMMANDED CLIMB. DISCONNECTED AUTOPILOT TO CONTINUE DESCENT. RESET AUTOPILOT WITH NO FURTHER PROBLEMS. IN FCC DIAGNOSTICS FOUND ESVOR AT 1.25VDC ON BOTH LT AND RT. SHOULD BE BELOW +/- .20VDC. NO REPAIR CODES STORED ON FCC DIAGNOSTIC PAGE. R & R ELEVATOR SERVO IAW AMM. OP'S CHECKED GOOD. FCC DIAGNOSTIC SHOWS NO REPAIR CODE BUT ESVOR SHOWS +/- .85VDC. IAW S/L FLIGHT DIRECTOR UNCOMMANDED CHANGES. QUARANTINED ELEVATOR SERVO.