What was found
AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED DUE TO: LOUD SQUEAL FROM CAPTIAN SLIDING WINDOW ON CLIMB. CHECKED WINDOW, WINDOW WAS LOCKED. SQUEAL LESSENED WHEN PRESSURE APPLIED TO HANDLE BUT NEVER WENT AWAY COMPLETELY; AIRCRAFT AIR INTERRUPTED BACK TO AND LANDED SAFELY AT DFW. REMOVED WINDOW, INSPECTED SEAL. NO ABNORMALITIES NOTED. PRESSURIZED TO 4 PSI. NO SQUEAL NOTED, PER AMM 56-12-11. NO FAULT FOUND.