What was found
CABIN DIFFICULT TO COOL. AFT CABIN COOLED OFF AFTER 1.5 HRS. ACFT GROUNDED. BITE PACK/ZONE TEMP CONTROLLER. NO FAULTS REF FIM 21-62, TASK 801. ACCOMPLISHED MIX MANIFOLD AND PACK TEMPERATURE SENSOR TESTS. TESTS PASS FOR BOTH SIDES. REINSTALLED AND BITE CHECKED BOTH PACK/ZONE TEMP CONTROLLERS. BITE TEST PASSES. NO FAULTS, REF FIM 21-62/849 AND 850. RAN ENGINE & PACKS. OPS CHECKED CABIN FWD & AFT TEMP, FROM COLD TO HOT. DUCT TEMP 7 CABIN HEATED 7 COOLED NORMAL. AFT CABIN COOLED WITH NO PROBLEM & INDICATIONS IN COCKPIT SHOWED SAME. OPS NORMAL IAW MM 21-61-00-700-807-002.