Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine
Situational Awareness
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Returned To Departure Airport; General Maintenance Action; General Flight Cancelled / Delayed
Aircraft
The left air conditioning pack was deferred. On climb out; passing through 4;000 ft.; we got an EICAS red warning message R BLEED DUCT which changed to amber after about 10 seconds. We ran the QRH and returned to CLT unpressurized. We contacted the company; cabin crew; and ATC.Likely the increased demands on the remaining air conditioning pack with climb thrust.
CRJ-700 Captain reported an EICAS red and amber warning that resulted in an air return.