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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 194 (Heater Systems) >> Symptom Tests >> Test H: HVAC Module Noise Diagnosis

Test H: HVAC Module Noise Diagnosis

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2002 GMC Savana Special, 2002 GMC Savana Camper Special, 2002 GMC Savana, 2002 Chevrolet RV Cutaway, and 2002 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: For circuit reference, see CONNECTOR IDENTIFICATION  and/or WIRING DIAGRAMS  .
NOTE: The manufacturer does not separate testing by "heater only" or "air conditioned" vehicles. References to air conditioning operations or repairs may not apply to vehicles without air conditioning. References to some components also may not apply to vehicles without air conditioning.
  1. Were you sent here from SYMPTOM DIAGNOSIS? If so, go to next step. If not, go to SYMPTOM DIAGNOSIS  under TROUBLE SHOOTING.
  2. Start the engine. Cycle through all of the blower motor speeds and the HVAC modes temperature control settings. Determine the type of noise:
    • Scrape
    • Pop
    • Tick/Click
    • Chirp
    • Groaning
    • Air Rush/Whistle
    Is a scrape or pop noise evident when selecting modes or temperature settings? If so, go to step  6. If not, go to next step.
  3. Is a tick/click, chirping, groaning or scraping noise present, but decreases as blower motor speed is decreased? If so, go to step  6. If not, go to next step.
  4. Is an air rush/whistle noise evident in all modes but not all temperature settings? If so, go to step  6. If not, go to next step.
  5. Is an air rush/whistle noise evident only in defrost or floor mode? If so, go to next step. If not, go to next step.
  6. Remove the I/P carrier. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Go to next step.
  7. Inspect the air flow doors for proper operation. Inspect the ducts for obstructions or foreign materials. Were any of these conditions found? If so, go to step  10. If not, go to next step.
  8. Inspect the mode and temperature doors and seals for warping or cracking. Are the doors in normal condition? If so, go to next step. If not, go to step  12.
  9. Replace the appropriate door and/or seals. See REMOVAL & INSTALLATION . After repairs are complete, go to step  11.
  10. Remove any obstructions or foreign material found. After repairs are complete, go to next step.
  11. Install the I/P carrier. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. After repairs are complete, go to next step.
  12. Operate the system to verify the repair. Is the system okay? If so, system is okay. If not, go to step  2.
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