What was found
DURING CLIMB, THE ACFT WOULD NOT PRESSURIZE. LEVELED AT 10,000 FEET, COMPLIED WITH AOM VOL 1 PROCEDURES. RETURNED TO DEPARTURE & LANDED WITHOUT INCIDENT. R & R CABIN PRESSURE CONTROL PANEL IAW AMM 21-33-01, OPS CHECKED GOOD, PRESSURIZED ACFT IN MM IAW AMM 21-31-00, ACFT HELD 3.8 DELTA PSI FOR OVER 3 MINUTES, NO LEAKS NOTED AT THIS TIME.