What was found
(CAN) FLIGHT DEPARTED UNDER MEL 36-00-00-A1, BLEED NR 1 INOPERATIVE. IN THE CLIMB AT FL240, THE CREW BEGAN EXPERIENCING TROUBLE WITH THE NR 2 BLEED. THE FLIGHT BEGAN DESCENDING AND THE QRH WAS FOLLOWED. THE CREW FELT THAT THE BLEED HAD STABILIZED AND BEGAN TO CLIMB AGAIN BUT WHEN REACHING FL210 THE BLEED ONCE AGAIN BEGIN TO FAIL. THE CREW DESCENDED TO A100 AND IN CONSULTATION WITH DISPATCH AND MAINTENANCE CONTROL ELECTED TO RETURN. THE DUTY PILOT WAS ADVISED. NO ADVERSE REACTION FROM THE PASSENGERS WAS EVIDENT. NR 2 ENGINE PRECOOLER REPLACED IAW AMM36-11-08. SERVICEABLE.