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HOMESERVICE MANUALSCHEVROLET2003TRAILBLAZER 4.2 S, 4WDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 1375 (HEATING, VENTILATION AND AIR CONDITIONING)REPAIR INSTRUCTIONSHVAC MODULE ASSEMBLY REPLACEMENTINSTALLATION PROCEDURE
2003 Chevrolet TrailBlazer 4.2 S, 4WD

Installation Procedure

2003 Chevrolet TrailBlazer 4.2 S, 4WDSECTION Installation Procedure
WARNING: This page is about a different car, the 2004 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.
    Fig 1: HVAC Module Assembly, Rear Heater Ducts And Nuts
    GM834531Courtesy of GENERAL MOTORS CORP.
  1. Install the HVAC module assembly (1) to the vehicle.
    2. NOTE: Refer to Fastener Notice in Cautions and Notices.
  2. Install the four nuts (2).

    Tighten:  Tighten the nuts (2) to 10 N.m (89 lb in).

  3. Connect the rear heater ducts (3) to the HVAC module assembly (1).
  4. Connect the blower motor electrical connector.
  5. Install the instrument panel reinforcement. Refer to Instrument Panel (I/P) Carrier Support Replacement in Instrument Panel, Gages, and Console.
  6. Install the instrument panel assembly. Refer to Instrument Panel (I/P) Trim Panel Replacement - Lower and Trim Pad Replacement - Instrument Panel (I/P) Upper in Instrument Panel, Gages, and Console.
  7. Install new O-rings lubricated with mineral base 525 viscosity refrigerant oil.
    8. Fig 2: Inlet Tube, Compressor, Suction Line, Bolts And Nuts
    GM833674Courtesy of GENERAL MOTORS CORP.
  8. Install the evaporator inlet (4) and outlet (3) tubes to the evaporator.
    9. Fig 3: Heater Core And Hoses
    GM244231Courtesy of GENERAL MOTORS CORP.
  9. Install the heater hoses (2,3) to the heater core.
  10. Fill the cooling system. Refer to Draining and Filling Cooling System .
  11. Evacuate and Recharge the A/C system. Refer to Refrigerant Recovery and Recharging.
  12. Connect the negative battery cable.

    Tighten:  Tighten the negative battery cable to 15 N.m (11 lb ft).

  13. Operate the A/C system and test for refrigerant leaks. Refer to Leak Testing .
RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.