GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2006 🢒 Yukon XL Denali 🢒 HVAC 🢒 Heating, Ventilation and Air Conditioning 🢒 Auxiliary Heater Pipe Replacement

Removal Procedure

    Object Number: 12777 Size: SH
  1. Drain the cooling system. Refer to Cooling System Draining and Filling in Engine Cooling.
  2. Squeeze the plastic retainer tabs on the inlet hose.

    3. Object Number: 12778 Size: SH
  3. Pull the connection apart.

    4. Object Number: 12777 Size: SH
  4. Squeeze the plastic retainer tabs on the outlet hose.

    5. Object Number: 12778 Size: SH
  5. Pull the connection apart.

    6. Object Number: 612571 Size: SH
  6. Remove the auxiliary heater pipes (1, 2) from the heater inlet and outlet tees (3, 4).
  7. Remove both of the right tires. Refer to Tire and Wheel Removal and Installation in Tires and Wheels.
  8. Remove the right rear wheelhouse panel. Refer to Rear Wheelhouse Inner Panel Extension Replacement in Body Rear End.
  9. Remove the right front wheelhouse panel. Refer to Wheelhouse Panel Replacement in Body Front End.

    10. Object Number: 612548 Size: SH
  10. Remove the auxiliary heater pipes (2, 3) from the auxiliary heater core.

    11. Object Number: 691870 Size: SH
  11. Remove the heater/A/C tubes retaining nut (4) from the stud (1) at the frame (6).
  12. Remove the auxiliary heater pipes (2) from the clamps (5).
  13. Remove the auxiliary heater pipes from the vehicle.

Installation Procedure
  1. Install the auxiliary heater pipes to the vehicle.

    2. Object Number: 691870 Size: SH
  2. Install the auxiliary heater pipes (2) to the clamps (5).

    3. Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  3. Install the heater/A/C tubes retaining nut (4) to the stud (1) at the frame (6).

    4. Tighten
    Tighten the nut to 7 N·m (62 lb in).


    Object Number: 612548 Size: SH
  4. Install the auxiliary heater pipes (2, 3) to the auxiliary heater core.
  5. Install the right front wheelhouse panel. Refer to Wheelhouse Panel Replacement in Body Front End.
  6. Install the right rear wheelhouse panel. Refer to Rear Wheelhouse Inner Panel Extension Replacement in Body Rear End.
  7. Install both of the right tires. Refer to Tire and Wheel Removal and Installation in Tires and Wheels.

    8. Object Number: 612571 Size: SH
  8. Install the auxiliary heater pipes (1, 2) to the heater inlet and outlet tees (3, 4).

    9. Object Number: 21855 Size: SH
  9. Connect the outlet heater hose to the heater core.
  10. Connect the inlet heater hose to the heater core.
  11. Fill the cooling system. Refer to Cooling System Draining and Filling in Engine Cooling.