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Too Cold In Vehicle (Auxiliary)

WARNING: This page is about a different car, the 2002 GMC Safari and 2002 Chevrolet Astro. 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: Definition: Auxiliary air temperature can not be adjusted from one or both auxiliary controls or auxiliary heating is insufficient.
  1. Did you review DESCRIPTION & OPERATION and perform the necessary inspections? If so, go to next step. If not, see DESCRIPTION , OPERATION  and TROUBLE SHOOTING  .
    2. NOTE: The auxiliary A/C system operates independently of the HVAC control assembly to provide heated airflow through the auxiliary system.
  2. Does the HVAC control assembly operate and provide sufficient heating? If so, go to next step. If not, see TOO COLD IN VEHICLE .
  3. Turn ignition on. Place the Heater and/or A/C auxiliary blower motor switch in each speed position. Does the auxiliary blower motor operate at all? If so, go to next step. If not, see AUXILIARY BLOWER MOTOR INOPERATIVE (A/C OR HEATER) .
  4. Does the auxiliary blower motor operate correctly for each speed position? If so, go to next step. If not, see AUXILIARY BLOWER MOTOR MALFUNCTIONS (A/C OR HEATER) .
  5. Is the vehicle equipped with an auxiliary A/C system? If so, go to next step. If not, go to step  8.
  6. Start the engine. Place the mode switch in the OFF or FLOOR positions. Does the A/C compressor operate? If so, see A/C COMPRESSOR CLUTCH DOES NOT DISENGAGE . If not, go to next step.
  7. Is the vehicle equipped with an auxiliary heating system? If so, go to next step. If not, system is operating as designed.
  8. Inspect the cooling system for the following:
    • Low coolant level.
    • Loose or worn accessory drive belt.
    • Leaking or kinked radiator or auxiliary heater hoses.
    • Missing radiator filler cap pressure seal.
    • Improper radiator filler cap operation.
    Did you find and correct the condition? If so, go to step  19. If not go to next step.
  9. Disconnect the vacuum hose from the coolant bypass valve. Start the engine. Place the auxiliary heater blower motor switch in the M1, M2 or M3 positions. Is there engine vacuum present at the coolant bypass valve vacuum hose? If so, see A/C PERFORMANCE TEST  under PERFORMANCE TESTS.
  10. Check the engine vacuum circuit of the auxiliary coolant bypass valve for a leak or blockage. Did you find and correct the condition? If so, go to step  19. If not, go to next step.
  11. Turn ignition off. Disconnect the coolant bypass valve solenoid connector. Connect a test light between the control circuit of the coolant bypass valve solenoid and ground. Turn ignition on. Place the auxiliary heater blower motor switch in the M1, M2 or M3 positions. Does the test light illuminate? If so, go to next step. If not, go to step  13.
  12. Check the ground circuit of the coolant bypass valve solenoid for an open. Did you find and correct the condition? If so, go to step  19. If not, go to step  15.
  13. Check the control circuit of the coolant bypass valve solenoid for a high resistance or an open. Did you find and correct the condition? If so, go to step  19. If not, go to next step.
  14. Check the control circuit of the coolant bypass valve solenoid for a short to voltage. Did you find and correct the condition? If so, go to step  19. If not, go to next step.
  15. Inspect the coolant bypass valve solenoid for poor connections. Did you find and correct the condition? If so, go to step  19. If not, go to step  17.
  16. Inspect the auxiliary heater blower motor switch 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 auxiliary coolant bypass valve. See COOLANT BYPASS VALVE  under REMOVAL & INSTALLATION. After repairs are complete, go to step  19.
  18. Replace the auxiliary heater blower motor switch. See AUXILIARY BLOWER SWITCHES  under REMOVAL & INSTALLATION. After repairs, go to next step.
  19. Operate the system in order to verify the repair. If system operates normally, repair is complete. If system still malfunctions, return to step  2.
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