What was found
CLT - FLT 1106 EN ROUTE CLT TO PHF. THE AFT CABIN TEMP AT 17,000 FEET BECAME UNBEARABLE. HOT AIR WAS REPORTED TO BE COMING OUT INTO THE REAR CABIN. THE FLIGHT CREW DECLARED AN EMERGENCY, AND RETURNED TO THE FIELD IN CLT. THE FLIGHT LANDED WITHOUT FURTHER INCIDENT. REMOVED AND REPLACED THE TRIM AIR MODULATING VALVE. ACTUATOR BINDING, SWITCHES OUT OF SPEC, RESISTOR ERRATIC.