What was found
PAX DOOR WARNING MSG IN FLIGHT, PEFORMED QRH FOLLOWED BY CABIN ALT, ALSO FOLLOWED BY PROX SYSTEM FAULT ONE STATUS MSG+MANAULLY DEPLOYED MASKS FA NOTED WHISTLINGS SOUND COMING FROM PAX / C/W FULL RIG CHECK OF PAX DOOR IAW CRJ900 AMM 52-11-00-720-802-A01. NO OUT OF RIG CONDITIONS NOTED NEUTRAL RIG MAINTAINED. C/W OPS CHECK OF PAX DOOR IAW CRJ900 AMM 52-11-00-710-801-A02, PAX DOOR OPERATION AND INDICATION ALL CHECKED GOOD.