What was found
ACFT WOULD NOT PRESSURIZE AFTER T/O RAN QRH PROCEDURES. NO HELP. CABIN SUPPLY TEMP REACHED 150F NO AIRFLOW AFTER T/O COULD FEEL AIRFLOW CYCLE 2 OR 3 TIMES ON THEN BACK OFF DURING FLIGHT. R & R LT PRSOV IAW AMM 21-31. LT FLOW CONTROL VALVE SLOW TO OPERATE. REPLACED SAME OPEN CKS AND LEAK CKS OK. REPLACED 575 DEGREE THERMOSTAT DUE TO AIR LEAKAGE IAW AMMM 21-61. PERFORMED SINGLE PACK CONFIDENCE CHECKS IAW AMM 21-00 AND HULL LEAK CHECK. PERFORMED ALL STEPS OF ODI PREVENTION WITH NO CONTAMINATION OF PNEU DUCTS, ENGINE AND ACFT SYSTEMS. C/W CARDS 2120-2367 AND 7100-2619, FULL DUCT BURN WITH NO ODORS NOTED.