What was found
FLT 1731JB JFK-BDA AIR TURNBACK TO JFK DUE TO LOUD SQUEAL COMING FROM DOOR 1R DURING CLIMBOUT AND AIRCRAFT WOULD NOT PRESSURIZE AT FL230 CABIN ALTITUDE READ 8000FT. JFK MX A/C R1 DOOR OK PER AMM 52-10-00, NO DEFECTS NOTED. ACCOMPLISHED FIM AMM TASK 21-31-00-810-818-A INSPECTED PACK BELLOWS IAW AMM 21-51-21. NO DAMAGE FOUND, FOUND ICING BUILD UP ON AIR CONDITIONER CHECK VALVE. CLEANED VALVE AND OPS CHECK OF VALVE OK PER AMM 21-20-02. NO DEFECTS NOTED ON VALVE. PERFORMED A/C PRESSURIZATION IAW AMM 21-31-00, NO NOISE OR LEAKS NOTED. AIRCRAFT HELD PRESSURE WITH NO FAULTS. OK FOR SERVICE.