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HOMESERVICE MANUALSCHEVROLET2001CHEVY EXPRESS G2500, VAN CARGO EXTENDED, 5.7 R, L31/KL8REPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 12 (HVAC SYSTEMS - AUTOMATIC)SYMPTOM TESTSTEST N: TEMPERATURE IS TOO COLD IN VEHICLE
2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8

Test N: Temperature Is Too Cold In Vehicle

2001 Chevrolet Chevy Express G2500, Van Cargo Extended, 5.7 R, L31/KL8SECTION Test N: Temperature Is Too Cold In Vehicle
WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
  1. Perform diagnostic system check. See DIAGNOSTIC SYSTEM CHECK  under SELF-DIAGNOSTIC SYSTEM. After performing system check, go to next step.
  2. Connect scan tool. Turn ignition ON. Using scan tool, perform RECALIBRATE ALL MOTORS command in IPM. Observe all current DTCs in Instrument Panel Module (IPM). If scan tool displays any DTCs, see DIAGNOSTIC TROUBLE CODE INDEX  table under SELF-DIAGNOSTIC SYSTEM. If DTCs are not displayed, go to next step.
  3. Place Blower Motor switch in each speed position. If Blower Motor operates in any position, go to next step. If Blower Motor does not operate in any position, see BLOWER MOTOR DOES NOT OPERATE IN ANY MODE  test.
  4. If Blower Motor operates in all speed positions, go to next step. If Blower Motor does not operate in all speed positions, see BLOWER MOTOR MALFUNCTION  test.
  5. If Blower Motor operates in all speed positions but problem only exists when heater or defrost is on, go to next step. If problem does not only exist when heater or defrost is on, go to step  9.
  6. Start engine. Turn HVAC controls OFF. If A/C compressor clutch engages, see COMPRESSOR CLUTCH DOES NOT DISENGAGE  test. If compressor clutch does not engage, go to next step.
  7. Inspect cooling system for low coolant level, leaking or kinked heater or radiator hoses, loose or worn drive belts or leaking radiator cap or missing cap seal. Correct any problems found and go to step  24. If no problems were found, go to next step.
  8. Check heating system performance. See HEATING SYSTEM PERFORMANCE  under SYSTEM TESTS. Correct any problems found and go to step  24. If no problems were found, go to next step.
  9. Inspect upper and lower, right and left, Air Temperature Sensors for proper installation. Correct any problems found and go to step  24. If no problems are found, go to next step.
  10. Start engine. Fully open all HVAC panel outlets. Place temperature switch at 75°F (24°C). Place mode switch in panel (upper) position. Set blower speed to illuminate 2 bars on fan speed indicator. Place Passenger's Temperature Switch in Neutral position. Test airflow through Inside Air Temperature Sensor by placing a 2" (5 cm) square piece of paper over sensor air inlet. If suction holds paper in place, go to next step. If suction does not hold paper in place, go to step  15.
  11. Turn ignition ON, engine OFF. Connect scan tool. Cover sunload sensor. Start engine. Place temperature switch at 75°F (24°C). Place Passenger's Air Temperature Switch in Neutral position. Using scan tool, observe both RIGHT and LEFT SOLAR SENSOR DATA parameters on INSTRUMENT PANEL MODULE (IPM) OPEN/SHORT data list. If scan tool indicates RIGHT and LEFT SUNLOAD SENSOR DATA parameters are more than 224 counts, go to next step. If scan tool indicates RIGHT and LEFT SUNLOAD SENSOR parameters are 224 counts or less, go to step  19.
  12. Uncover Sunload Sensor. Shine a light at right and then left side of Sunload Sensor assembly. If counts change in relation to amount of light and which side of Sunload Sensor assembly is being illuminated, go to next step. If counts do not change in relation to amount of light and which side of the Sunload Sensor assembly is being illuminated, go to step  19.
  13. Place thermometer near Inside Air Temperature Sensor and upper and lower right and left air temperature sensors. Using scan tool, observe DATA parameters in INSTRUMENT PANEL MODULE HVAC SENSOR data list for INSIDE AIR TEMP, RIGHT A/C DUCT TEMP, LEFT A/C DUCT TEMP, LEFT A/C DUCT TEMP, RIGHT HTR DUCT TEMP and LEFT HTR. DUCT TEMP. If scan tool readings are within 5°F to -5°F (3°C to -3°C) of thermometer readings, go to next step. If scan tool readings are not within 5°C to -5°F (3°C to -3°C) of thermometer readings, go to step  16.
  14. If customer needs to frequently change the set temperature to maintain comfort, see A/C SYSTEM DOES NOT MAINTAIN SET TEMPERATURE  test. If customer does not need to frequently change the set temperature to maintain comfort, go to step  18.
  15. Inspect for blocked or disconnected Aspiration Hose and repair as necessary and go to step  24.
  16. Check for poor connections at suspect air temperature sensor harness connector. If poor connection is found, repair as necessary. When repair is complete, go to step  24. If poor connection is not found, go to next step.
  17. Check resistance of suspect air temperature sensor. See SENSOR RESISTANCE  table under A/C SYSTEM DOES NOT MAINTAIN SET TEMPERATURE test. If sensor tests okay, go to step  20. If sensor does not test as specified, go to step  21.
  18. Connect scan tool. Turn ignition on. Using scan tool, perform ADJUST TEMPERATURE OFFSET in INSTRUMENT PANEL MODULE SPECIAL FUNCTION/SET options as needed. When complete, go to step  24.
  19. Check Sunload Sensor for loose wires and connector. Repair as necessary and go to step  24. If poor connection is not found, go to step  22.
  20. Check for loose wires and/or poor connections at IPM. Repair as necessary and go to step  24. If poor connection is not found, go to step  23.
  21. Replace suspect sensor, see AIR TEMPERATURE SENSORS  under REMOVAL & INSTALLATION and go to step  24.
  22. Replace Sunload Sensor, see SUN LOAD SENSOR  under REMOVAL & INSTALLATION and go to step  24.
  23. Replace IPM, see INSTRUMENT PANEL MODULE (IPM)  under REMOVAL & INSTALLATION and go to step  24.
  24. Operate system to verify repair. If condition is corrected, system is okay. If condition is not corrected, go to step  2.
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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.