What was found
AFTER TAKE OFF, ALL AIRFLOW STOPPED. BOTH PACK FLOW CONTROL VALVES SHOWED CLOSED. CABIN SLOWLY CLIMBED AT 300-400 FPM UNTILL 10,000 CABIN ALTITUDE DURING CLIMB, TRIED RUNNING PACKS IN MANUAL, CYCLED PACK VALVES WITH NO LUCK. CYCLED REGULATOR AND SYS SWITCHES. NO LUCK. REPLACED RELAYS 31HB, 61GB, AND 181HB. IAW ESPM 20-46-50. RAN APU IAW JRH AND BOTH PACKS NR 1 AND 2 OPERATED NORMAL. OPERATED PACKS IN MANUAL AS WELL AS AUTO, AND EACH PACK INVIDUALLY WITH NO FAULTS NOTED. IAW AMM 21-51-00-05. ACFT OK TO CONTINUE.