What was found
CABIN ALT INCREASED ABNORMALLY IN CONJUNCTION WITH INDICATED ALT. DIFFERENTIAL PRESS WAS 0-1 P.S.I. AIRCRAFT NEVER PRESSURIZED WHEN WE DID RESET THE PACKS.-C/A-REMOVED AND REPLACED ELECTROPNEUMATIC OUTFLOW VALVE IAW EMB 140 AMM 21-31-03. NO DEFECTS NOTED. REMOVED AND REPLACED DIGITAL CONTROLLER IAW EMB 140 AMM 21-31-01, FOR PRECAUTIONARY PURPOSES. PERFORMED MANUAL MODE PRESSURIZATION CHECK IAW EMB140 AMM 21-31-00. OPC GOOD OF MANUAL PRESSURIZATION. NO DEFECTS NOTED AT THIS TIME. PERFORMED PRESS TEST IAW EMB AMM 21-31-00 PRESS TEST GOOD NO DEFECTS NOTED.