What was found
UNABLE TO CONTROL CABIN TEMP IN AUTOMODE. TROUBLESHOT AND FOUND DEBRIS IN CABIN CONDITIONED AIR DUCT CHECK VALVE. REMOVED CHECK VALVE TO REMOVED DEBRIS. FOUND CABIN MIXING MUFF AND COCKPIT MIXING MUFF DELAMINATING ON THE INSIDE. REMOVED LT AND RT MUFFS AND DUCTING REF MM 21-21-03. RE-INSTALLED SAME SERVICABLE CABIN COND AIR DUCT CHECK VALVE REF MM 21-22-01. INSTALLED NEW LT AND RT MIXING MUFFS (PN: 6915030-8) AND REINSTALLED DUCTING REF MM 21-21-03. PERFORMED GROUND RUN NO LEAKS NOTED. PERFORMED CABIN AUTO TEMP CHECK REF MM 21-22-00. OPS CHECK GOOD.