Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Issued New Clearance; Flight Crew Took Evasive Action; Flight Crew Overcame Equipment Problem
Weather; Aircraft; MEL
At around F230 we [encountered] icing [so] I turned on wing and cowl anti ice. Moments later received L BLEED DUCT warning. Captain ran QRH. QRH requires operating pack off and Isolation (ISOL) valve closed. It doesn't account for our MEL Ram Air Shutoff Valve which requires right pack OFF. Now without pressurization cabin altitude was climbing around 1;000 feet per minute. Which until we got our descent going and changed ISOL back opened and turned left pack back on cabin climbed to around 9;200 feet. We descended out of icing to around 12;000 feet. Captain had [advised ATC of] the descent and notified inflight crew which we had asked for 10;000 I believe; but after we realized we would get back in icing we decided to stay where we were to stay between layers and at around Total Air Temperature (TAT) 22 C. We asked ATC and they gave us 14;000 feet [because] of no anti icing equipment. Somewhere in the descent I asked the Captain to start the APU which could have also covered our pressurization but we elected to use the right bleed source instead; but had as a backup. The Captain had notified dispatcher via ACARS. We had plenty of fuel to stay at lower altitude.Company could fix airplanes in a more timely matter instead of sending aircraft into icing conditions with this deferral.
CRJ-700 FO reported loss of L BLEED DUCT which; when combined with an existing MEL; resulted in loss of cabin pressure. Flight descended out of icing conditions and continued to destination.