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Test L: Too Hot In Vehicle (Auxiliary)

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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.
NOTE: Definition: The auxiliary temperature can not be adjusted from one or both auxiliary controls or auxiliary cooling insufficient.
  1. Did you review the DESCRIPTION  and OPERATION  and perform the necessary inspections? If so, go to next step. If not, go to DESCRIPTION  and OPERATION  , then go to next step.
  2. Turn the ignition on, with the engine off. Place the mode switch in any position except Off. Place the auxiliary blower control in each speed position. Does the auxiliary blower motor operate in any of the speed positions? If so, go to next step. If not, go to TEST B: AUXILIARY BLOWER MOTOR INOPERATIVE .
  3. Does the auxiliary blower motor operate correctly for each speed position? If so, go to next step. If not, go to TEST C: AUXILIARY BLOWER MOTOR MALFUNCTION .
  4. Start the engine. Place the blower motor switch in the maximum speed position. Place the mode switch in the BI-LEVEL position. Place the temperature switch in the coldest position. Does the A/C compressor operate? If so, go to next step. If not, see appropriate HVAC COMPRESSOR CLUTCH DOES NOT ENGAGE in SYMPTOM TESTS in MANUAL A/C-HEATER SYSTEMS article.
  5. Perform the A/C PERFORMANCE TEST. See A/C PERFORMANCE TEST in PERFORMANCE TESTS in MANUAL A/C-HEATER SYSTEMS article. Did you find and correct the condition? If so, go to step  37. If not, go to next step.
  6. Does the TOO HOT IN VEHICLE (AUXILIARY) condition happen with both the front and rear auxiliary HVAC control assemblies? If so, go to step  9. If not, go to next step.
  7. Does the TOO HOT IN VEHICLE (AUXILIARY) condition happen only with front auxiliary HVAC control assembly? If so, go to step  13. If not, go to next step.
  8. When the heater or the defroster is on, does the customer concern occur? If so, go to step  16. If not, go to TEST K: TOO HOT IN VEHICLE .
  9. Turn the ignition on, with the engine off. Observe the auxiliary temperature actuator. Place the front auxiliary temperature switch from the coldest position to the warmest position. Does the temperature actuator move with a smooth transition between cold and hot? If so, condition is intermittent. See SYMPTOM DIAGNOSIS  under TROUBLE SHOOTING. If not, go to next step.
  10. Disconnect the auxiliary temperature actuator. Place the blower motor switch on the front auxiliary HVAC control assembly to any position except REAR CNTL or OFF. Measure the voltage from the auxiliary temperature door control circuit of the auxiliary temperature actuator to ground while turning the auxiliary temperature control from cold to hot. Does the measured voltage range from zero volts to battery voltage? If so, go to next step. If not, go to step  20.
  11. Connect a test light between the ignition 3 voltage circuit and the ground circuit of the auxiliary temperature actuator. Does the test light illuminate? If so, go to step  19. If not, go to next step.
  12. Connect a test light between the ignition 3 voltage circuit and ground. Does the test light illuminate? If so, go to step  21. If not, go to step  22.
  13. Disconnect the auxiliary HVAC control processor. Place the blower motor switch on the front auxiliary HVAC control assembly to any position except REAR CNTL or OFF. Turn the front auxiliary temperature control switch from the coldest position to the warmest position. Measure the voltage from the front auxiliary HVAC control assembly on the auxiliary temperature door control circuit to ground. Does the measured voltage range from zero volts to battery voltage? If so, go to next step. If not, go to step  23.
  14. Place the front auxiliary blower motor switch to any position except REAR CNTL or OFF. Connect a test light between the ignition 3 voltage circuit of the front HVAC control assembly and auxiliary blower motor switch control circuit to the front auxiliary HVAC control assembly. Does the test light illuminate? If so, go to step  24. If not, go to next step.
  15. Connect a test light between the ignition 3 voltage circuit and ground. Does the test light illuminate? If so, go to step  30. If not, go to step  25.
  16. Disconnect the auxiliary HVAC control processor. See AUXILIARY HVAC CONTROL PROCESSOR  under REMOVAL & INSTALLATION. Place the blower motor switch on the front auxiliary HVAC control assembly to the REAR CNTL position. Turn the rear auxiliary temperature control switch from the coldest position to the warmest position. Measure the voltage from the rear auxiliary HVAC control assembly to the auxiliary temperature door control circuit to ground. Does the measured voltage range from zero volts to battery voltage? If so, go to next step. If not, go to step  26.
  17. Place the blower motor switch on the front auxiliary HVAC control assembly to the REAR CNTL position. Connect a test light between the ignition 3 voltage circuit of the rear HVAC control assembly and auxiliary blower motor switch control circuit to the front auxiliary HVAC control assembly. Does the test light illuminate? If so, go to step  25. If not, go to next step.
  18. Connect a test light between the ignition 3 voltage circuit of the rear auxiliary HVAC control assembly and ground. Does the test light illuminate? If so, go to step  27. If not, go to step  28.
  19. Inspect the auxiliary temperature door and the auxiliary temperature actuator for the following conditions:
    • Misaligned Auxiliary Temperature Actuator
    • Broken Or Binding Linkages Or Temperature Door
    • Obstruction That Prevents The Temperature Door From Operating Within Its Full Range Of Motion
    • Missing Seals To The Auxiliary Temperature Door
    • Misaligned Seals To The Auxiliary Temperature Door
    Did you find and correct the condition? If so, go to step  37. If not, go to step  29.
  20. Check the auxiliary temperature door control circuit of the auxiliary temperature actuator from the front auxiliary HVAC control assembly to the auxiliary temperature actuator for an open, high resistance, short to ground, or short to voltage. Did you find and correct the condition? If so, go to step  37. If not, go to step  25.
  21. Check the ground circuit of the auxiliary temperature actuator for an open or high resistance. Did you find and correct the condition? If so, go to step  37. If not, go to step  29.
  22. Check the ignition 3 voltage circuit actuator for an open or a high resistance. Did you find and correct the condition? If so, go to step  37. If not, go to step  29.
  23. Check the auxiliary temperature door control circuit of the auxiliary temperature actuator from the front auxiliary HVAC control assembly to the auxiliary HVAC control processor for an open, high resistance, short to ground, and short to voltage. Did you find and correct the condition? If so, go to step  37. If not, go to step  30.
  24. Check the auxiliary blower motor switch control circuit for short to ground. Did you find and correct the condition? If so, go to step  37. If not, go to step  30.
  25. Check the ignition 3 voltage circuit of the auxiliary HVAC control processor for an open or a high resistance. Did you find and correct the condition? If so, go to step  37. If not, go to step  32.
  26. Check the auxiliary temperature door control circuit of the auxiliary temperature actuator from the rear auxiliary HVAC control assembly to the auxiliary HVAC control processor for an open, high resistance, short to ground, and short to voltage. Did you find and correct the condition? If so, go to step  37. If not, go to step  31.
  27. Check the auxiliary blower motor switch control circuit for an open or high resistance. Did you find and correct the condition? If so, go to step  37. If not, go to step  31.
  28. Check the ignition 3 voltage circuit of the rear auxiliary HVAC control assembly for an open or a high resistance. Did you find and correct the condition? If so, go to step  37. If not, go to step  31.
  29. Inspect for poor connections at the harness connector of the auxiliary temperature actuator. Did you find and correct the condition? If so, go to step  37. If not, go to step  33.
  30. Inspect for poor connections at the harness connector of the front auxiliary HVAC control assembly. Did you find and correct the condition? If so, go to step  37. If not, go to step  34.
  31. Inspect for poor connections at the harness connector of the rear auxiliary HVAC control assembly. Did you find and correct the condition? If so, go to step  37. If not, go to step  35.
  32. Inspect for poor connections at the harness connector of the auxiliary HVAC control processor. Did you find and correct the condition? If so, go to step  37. If not, go to step  36.
  33. Replace the auxiliary temperature actuator. See AUXILIARY TEMPERATURE ACTUATOR  under REMOVAL & INSTALLATION. After repairs are complete, go to step  37.
  34. Replace the front auxiliary HVAC control assembly. See AUXILIARY HVAC CONTROL ASSEMBLY (FRONT)  under REMOVAL & INSTALLATION. After repairs are complete, go to step  37.
  35. Replace the rear auxiliary HVAC control assembly. See AUXILIARY HVAC CONTROL ASSEMBLY (REAR)  under REMOVAL & INSTALLATION. After repairs are complete, go to step  37.
  36. Replace the auxiliary HVAC control processor. See AUXILIARY HVAC CONTROL PROCESSOR  under REMOVAL & INSTALLATION. After repairs are complete, go to step  37.
  37. 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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