GM 52478848
Heater Core

Refrigerant recovery along with engine coolant draining must take place before starting the heater core replacement of the auxiliary HVAC module. First lift the vehicle and cut all connections between the heater lines (2,3) and air conditioning lines (2,3) at the auxiliary HVAC module underneath. Remove the nuts retaining the auxiliary HVAC module to the vehicle before you remove safety stands and lower the vehicle. Begin by removing the right rear quarter trim panel together with the Real Time Damping (RTD) Module while disconnecting their electrical connectors. Insert the duct through the opening of the headliner as you gently raise it upward. Then remove the lower and upper auxiliary air duct fasteners separately. The fasteners for both the lower auxiliary air outlet and the air distributor duct need removal before extracting the air distributor duct. Start by removing fasteners number 2 and 4 which keep the rear auxiliary HVAC module secured and take the module out to work on a surface. Remove the air temperature actuator from the module until the heater core pipe retainer along with its gasket can be properly separated from the module case between the inlet and outlet pipes. First remove the rear HVAC module lower cover followed by the heater core clamp before taking off the heater core itself. Set the heater core into its installation position inside the module before using the heater core clamp to fasten everything. Replace the rear HVAC module lower cover before installing the heater core pipe retainer and gasket as well as the stud linking the heater core inlet to the outlet. The air temperature actuator along with the auxiliary HVAC module assembly should be reinstalled to the vehicle with two bolts attaching them at points 2 and 4. Secure the lower auxiliary air outlet with fastener and the upper auxiliary air duct to the air distributor duct also with fastener. The electrical connectors must be connected while reinstalling the RTD Module and right rear quarter trim panel. After placing the vehicle higher again perform nut installation on the auxiliary HVAC module with a torque of 9 N.m (80 lb in). Screw the nut on the auxiliary HVAC module while tightening it to 16 N.m (12 lb ft) before joining heating lines (2,3) at the underside of the module. Proceed with van electrical system operation and lower the vehicle using tools and safety equipment. Then follow up by filling the engine coolant and recharging the refrigerant to the system.

Remove the auxiliary HVAC module from the vehicle.

Reattach the auxiliary HVAC module lower cover.

Install the stud between the heater core inlet and outlet on the underside of the rear HVAC module.