Narrative:

After pushback with engines running; flight attendant called flight deck reporting light smoke and fumes in cabin. Myself and first officer noticed a light smell of fumes in the flight deck without the presence of smoke. While I was talking to the flight attendants over the intercom first officer noticed the left pack autofail caution msg came on. I got off the phone with the flight attendants and called for emergency checklist smoke and fume removal. After looking at the checklist; I determined it was not necessary and called for QRH left pack autofail checklist. QRH directed us to select manual mode and manually control temp with toggle switch. The first officer and I try to cool down the output temp by holding down the toggle switch for several seconds without any success. The output temp readout was at 99 degrees celsius. After pressing manual mode; left pack autofail msg went away and then followed by left pack temperature caution msg came on. By this time; I have made a few announcements to the passengers to keep them informed of the situation and had by this point 2 conversations with both flight attendants of the situation. The second conversation with the flight attendants; the flight attendant called over the emergency intercom to tell us that the passenger in xxa had a hot seat. I asked them to keep me posted and told them that the cause of the hot seat and hot temp in the back of the plane was due to a broken left pack. After not able to cool the output of the left pack; I called for QRH left pack temperature checklist and the QRH directed us the turn off the left pack. I asked the first officer to call operations and ground to coordinate a gate return. Ground acknowledged request; but no answer on operations frequency. First officer called ops on the phone and was able to get a hold of them and we told them we needed to return to the gate to deplane passengers. Ops acknowledge request; but no action was taken for a few minutes. While first officer was coordinating a gate return; I was talking to flight attendants about cabin status. The flight attendants reported that cabin condition was improving. Fumes and smoke were dissipating and temperature was starting to cool down. We waited a few more minutes to hear back from ops to get a ramp crew out to park us with no results. I called them over the phone myself to expedite our return to the gate. Ops told us that they were working on it. A few seconds went by and we got a call from ops over frequency asking to push another aircraft before they would come over and park us back at gate. We declined their request and ask to be parked first. They asked if this was an priority handling and to expedite our return to the gate I [advised]. We returned to the gate and a police officer boarded the plane to assist and assess the situation. We had to deplane the passengers using the passenger door due to the ground crew parked us short and the jet bridge couldn't reach the plane.the cause of the light smoke and fumes in the cabin was due to the left pack malfunctioned and broken causing dust and water vapor to enter the cabin. The hot aft cabin also due to hot temperature output by the left pack. We expedited our return to the gate; because we would have sat there for a while waiting for ramp personnel to park us.

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Original NASA ASRS Text

Title: CRJ-900 flight crew reported Flight Attendant notification of light smoke and fumes in the cabin followed shortly by experiencing fumes on the flight deck after pushback.

Narrative: After pushback with engines running; Flight Attendant called flight deck reporting light smoke and fumes in cabin. Myself and First Officer noticed a light smell of fumes in the flight deck without the presence of smoke. While I was talking to the flight attendants over the intercom First Officer noticed the L PACK AUTOFAIL caution msg came on. I got off the phone with the flight attendants and called for Emergency Checklist smoke and fume removal. After looking at the checklist; I determined it was not necessary and called for QRH L PACK AUTOFAIL checklist. QRH directed us to select Manual Mode and manually control Temp with toggle switch. The First Officer and I try to cool down the output temp by holding down the toggle switch for several seconds without any success. The output temp readout was at 99 degrees Celsius. After pressing Manual mode; L PACK AUTOFAIL msg went away and then followed by L PACK TEMP caution msg came on. By this time; I have made a few announcements to the passengers to keep them informed of the situation and had by this point 2 conversations with both flight attendants of the situation. The second conversation with the flight attendants; the Flight Attendant called over the Emergency intercom to tell us that the passenger in XXA had a hot seat. I asked them to keep me posted and told them that the cause of the hot seat and hot temp in the back of the plane was due to a broken L pack. After not able to cool the output of the L Pack; I called for QRH L PACK TEMP checklist and the QRH directed us the turn off the Left pack. I asked the First Officer to call OPS and Ground to coordinate a gate return. Ground acknowledged request; but no answer on OPS frequency. First Officer called Ops on the phone and was able to get a hold of them and we told them we needed to return to the gate to deplane passengers. Ops acknowledge request; but no action was taken for a few minutes. While First Officer was coordinating a gate return; I was talking to flight attendants about cabin status. The flight attendants reported that cabin condition was improving. Fumes and smoke were dissipating and temperature was starting to cool down. We waited a few more minutes to hear back from Ops to get a ramp crew out to park us with no results. I called them over the phone myself to expedite our return to the gate. Ops told us that they were working on it. A few seconds went by and we got a call from Ops over frequency asking to push another aircraft before they would come over and park us back at gate. We declined their request and ask to be parked first. They asked if this was an priority handling and to expedite our return to the gate I [advised]. We returned to the gate and a police officer boarded the plane to assist and assess the situation. We had to deplane the passengers using the passenger door due to the ground crew parked us short and the jet bridge couldn't reach the plane.The cause of the light smoke and fumes in the cabin was due to the Left pack malfunctioned and broken causing dust and water vapor to enter the cabin. The hot aft cabin also due to hot temperature output by the Left pack. We expedited our return to the gate; because we would have sat there for a while waiting for ramp personnel to park us.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.