On 14 June, 2003, Boeing 737-340 aircraft (AP-BCD) departed from lslamabad to Lahore. During cruise, the crew experienced an increase in the left duct pressure (60 psi), whereas the right duct pressure was within the limrts (40 psi). The crew kept the air mixture valve on maximum (full cold pos1t1on), but the cabin temperature continued to increase. Ventilation of the cabin was normal with both the air conditioning packs on 'High' position. On ground, the heat exchanger was serviced and then the packs performances were checked as per maintenance manual. Both packs were found to be satisfactory by the Aircraft Maintenance Engineer. The aircraft flew 05 sectors flight without encountering any problem related to the air conditioning and pressurization system.
