What was found
F/A'S REPORT SEVERAL INTERMITTENT INSTANCES OF EXTREMELY HOT AIR FROM ROW 6 TO ROW 12. SEVERAL MINOR ADJUSTMENT TO FWD CAB HAD NO EFFECT. ONLY AFTER TURNING FWD CAB EXTREMELY LOW DID THE ISSUE RESOLVE. TO MAINTAIN ACCEPTABLE TEMP FROM ROW 6-12, FWD CABIN TEMP SELECTED VERY LOW AND AFT CABIN SELECTED HIGHER. SYS WAS PRODUCING AIR TOO HOT ROW 6-12 WHEN CONFIGURED NORMALLY. ACFT GROUNDED. FOUND BOTH CABIN TEMP FILTER SCREENS CLOGGED, CLEANED SAME. BOTH ZONE CONTROLLERS BITE CHECK GOOD IAW AMM 21-61-00. SYS OPS CHECKS NORMAL, GROUND VERIFICATION SUCCESSFUL.