What was found
DISPLAY COOL MESSAGE IN FLIGHT. COMPLIED WITH QRH PROCEDURE BUT DISPLAY COOL MESSAGE PERSISTED UNTIL GEAR DOWN. RETURNED TO DFW.INSTALLED SERVICEABLE DISPLAY COOLING AIR FILTER IAW MM 21-21-15.
As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
DISPLAY COOL MESSAGE IN FLIGHT. COMPLIED WITH QRH PROCEDURE BUT DISPLAY COOL MESSAGE PERSISTED UNTIL GEAR DOWN. RETURNED TO DFW.INSTALLED SERVICEABLE DISPLAY COOLING AIR FILTER IAW MM 21-21-15.