As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
LAS - UPON TAKEOFF LT AIR COND TEMP HIGH LIGHT CAME ON DURING T/O POWER. COMPLETED AIR COND TEMP HIGH CHECK LIST, LT PACK CONTINUED TO INDICATE ZERO. RETURNED TO LAS. REPLACED LT PACK AIR FLOW TRANSMITTER. LEAK CHECK OK. NO HELP. FOUND PRESS REGULATOR VALVE OPEN. REMOVED AND REPLACED PRESS REGULATOR VALVE. PNEUMATIC SYSTEM PRESS TEST, LEAK CHECK NORMAL. AIRCRAFT RETURNED TO SERVICE. (M)