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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> Heating, Ventilation & A/C (HVAC) >> HVAC Control Systems >> Heater Systems >> Symptom Tests >> Test "G": Too Hot In Vehicle

Test "G": Too Hot In Vehicle

NOTE: For circuit reference, see CONNECTOR IDENTIFICATION  and/or WIRING DIAGRAMS  .
NOTE: This test applies to heater only and air conditioned vehicles. For heater only vehicles, disregard references to air conditioning checks and procedures.
NOTE: Definition: The temperature can not be adjusted, or the cooling is insufficient during A/C operation.
  1. Did you perform the HVAC Diagnostic System Check? If so, go to next step. If not, see DIAGNOSTIC SYSTEM CHECK  under TROUBLE SHOOTING.
  2. Turn the ignition on, with the engine off. Place the mode switch in any position except OFF. Place the blower motor switch in each speed position. Does the blower motor operate at all? If so, go to next step. If not, go to TEST "C" BLOWER MOTOR INOPERATIVE .
  3. Does the blower motor operate in each of the speed positions? If so, go to next step. If not, go to TEST "D" BLOWER MOTOR MALFUNCTION .
  4. Alternate between MAX A/C (if equipped) and vent positions. Does the recirculation door move from the recirculate position to the outside air position? If so, go to next step. If not, go to TEST "A" AIR DELIVERY IMPROPER .
  5. Does the too hot in vehicle concern occur when A/C cooling is desired? If so, go to next step. If not, go to step  8.
    6. NOTE: For A/C compressor operation, ambient air temperature must be above 38°F (3°C).
  6. Start the engine. Place the blower motor switch in the maximum speed position. Place the mode switch in the MAX position. Place the air temperature switch in the coldest position. Does the A/C compressor clutch engage? If so, go to next step. If not, see COMPRESSOR CLUTCH DOES NOT ENGAGE procedure in MANUAL A/C-HEATER SYSTEMS article.
  7. Perform the A/C System Performance Test. See A/C PERFORMANCE TEST procedure in PERFORMANCE TESTS article. Did you find and correct the condition? If so, go to step  19. If not, go to next step.
  8. Observe the shaft of the air temperature actuator. Place the air temperature switch from the coldest position to the warmest position. Does the shaft of the air temperature actuator rotate? If so, go to next step. If not, go to step  10.
  9. Inspect the air temperature door and the air temperature actuator for the following conditions:
    • Misaligned Air Temperature Actuator
    • Broken Or Binding Linkages Or Air Temperature Door
    • Obstruction That Prevents The Air Temperature Door From Operating Within Its Full Range Of Motion
    • Missing Seals To The Air Temperature Door
    • Misaligned Seals To The Air Temperature Door
    Did you find and correct the condition? If so, go to step  19. If not, problem is intermittent. See SYMPTOM DIAGNOSIS  under TROUBLE SHOOTING.
  10. Test the air temperature actuator ignition voltage circuit for an open or a high resistance. Did you find and correct the condition? If so, go to step  19. If not, go to next step.
  11. Test the air temperature actuator ground circuit of for an open or high resistance. Did you find and correct the condition? If so, go to step  19. If not, go to next step.
  12. Test the air temperature actuator control circuit for an open, high resistance, short to ground, or short to voltage. Did you find and correct the condition? If so, go to step  19. If not, go to next step.
    13. NOTE: Ensure that the HVAC control assembly connector is connected during this step to avoid misdiagnosis.
  13. Turn the ignition on, with the engine off. Measure the voltage from harness connector terminal No. 8 of the air temperature actuator to ground. Place the air temperature switch from the coldest position to the warmest position. Does the voltage measure between 12 volts (cold) to zero volts when in (hot) position, with a smooth transition between cold and hot? If so, go to next step. If not, go to step  16.
  14. Inspect the air temperature actuator for poor connections. Did you find and correct the condition? If so, go to step  19. If not, go to next step.
  15. Inspect the air temperature actuator door and any attaching linkage for binding or a condition that prevents drive shaft rotation. Did you find and correct the condition? If so, go to step  19. If not, go to step  17.
  16. Inspect the HVAC control assembly for poor connections. Did you find and correct the condition? If so, go to step  19. If not, go to step  18.
  17. Replace the air temperature actuator. See TEMPERATURE DOOR ACTUATOR  under REMOVAL & INSTALLATION. After repairs, go to step  19.
  18. Replace the HVAC control assembly. See HVAC CONTROL ASSEMBLY  under REMOVAL & INSTALLATION. After repairs, go to next step.
  19. Operate the system in order to verify the repair. Did you correct the condition? If so, system is okay. If not, go to step  2.
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