Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Time Pressure; Troubleshooting
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Weight And Balance
Flight Crew Returned To Departure Airport; Flight Crew Overcame Equipment Problem
Human Factors; Aircraft
Left pack was deferred on airplane. Some kind of maintenance issue caused cabin alt to rise; resulting in the cabin alt amber caution message.On climb out; Aircraft X; we were climbing through about 25;000 feet and received a 'CABIN ALT' amber msg. We noted the cabin altitude was climbing through about 9;800 feet; and ascending at a fairly rapid rate. The Captain called for the 'CABIN ALT' msg Immediate Action Checklist; so we ran it. It then stated to go to [a specific emergency checklist]. It said the same thing and step 7 said to turn 'PASS OXY ON'. We selected it ON and the passenger oxygen masks dropped. We descended to 10;000 feet and completed the 'CABIN ALT' checklist; and got the cabin pressure back to a normal altitude. We decided to return back to ZZZ as a precaution. Looking back; it may have been more appropriate to initially run the abnormal checklist (since it was only a caution message); but given the cabin altitude seemed to be rising at a rapid rate; the Captain decided to proceed with the Immediate Action Checklist to remain on the conservative side of safety. We returned to ZZZ and decided to land about 2;000 lbs over weight so the uneasy passengers could get off the airplane.Would initially run abnormal checklist as opposed to Immediate Action Checklist. On Immediate Action Checklist; it only says 'CABIN ALT Msg or Emergency Descent Procedure' and then leads to [another emergency checklist].
CRJ-700 First Officer reported executing the Cabin Altitude checklist for a amber caution message when the Abnormal Checklist may have been more appropriate.