C 1500 Yukon XL 2WD V8-5.3L VIN T (2001)
17. Remove the air temperature actuator (1).
18. Remove the stud on the underside of the rear HVAC module between the heater core inlet and outlet pipes (4).
19. Carefully separate the heater core pipe gasket from the module case and remove the heater core pipe retainer.
20. Remove the rear HVAC module lower cover.
