LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2020 >> Express 2500 LS, 6.0L Eng VIN G >> Repair and Diagnosis >> External Pages >> Different car >> Section 79 (HVAC - Manual) >> Diagnostic Information and Procedures >> Blower Motor Malfunction >> Circuit/System Testing

Circuit/System Testing

WARNING: This page is about a different car, the 2019 GMC Savana 3500, 2019 GMC Savana 2500, 2019 Chevrolet Express 3500, and 2019 Chevrolet Express 2500. However, it is still accessible from the selected car via links, so may be relevant.
  1. Ignition OFF, disconnect the X2 harness connector at the HVAC control assembly.
  2. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal E and ground.
    • If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
  3. Ignition OFF, connect the X2 harness connector at the HVAC control assembly. Disconnect the X1 harness connector at the HVAC control assembly.
  4. Ignition ON, cycle the mode selector through each position. Verify a test lamp illuminates between the control circuit terminal A in each mode position.
    • If the test lamp does not illuminate in each position, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the HVAC control assembly.
  5. Ignition OFF, connect the X1 harness connector at the HVAC control assembly. Disconnect the harness connector at the blower motor resistor assembly.
  6. Test for less than 5 ohms between the ground circuit terminal C and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance.
  7. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal A and ground.
    • If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  8. Mode selector set to Panel, while changing the fan speed switch between LOW, M1, M2 and HIGH, verify that a test lamp illuminates between the appropriate control circuit terminals listed below and ground:
    • LOW - terminal E
    • M1 - terminal D
    • M2 - terminal F
    • HIGH - terminal B
    • If the test lamp does not illuminate, test the appropriate control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the HVAC control assembly.
  9. Ignition OFF, connect the harness connector at the blower motor resistor assembly. Disconnect the harness connector at the blower motor.
  10. Test for less than 5 ohms between the ground circuit terminal A and ground.
    • If greater than the specified range, test the ground circuit for an open/high resistance. If the circuit tests normal, replace the blower motor resistor assembly.
  11. Ignition ON, mode selector set to Panel, connect a test lamp between the control circuit terminal B and ground circuit terminal A.
  12. Cycle the fan speed switch between LOW, M1, M2 and HIGH speeds. The test lamp should illuminate and change in intensity as the blower speed is varied.
    • If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the blower motor resistor assembly.
    • If the test lamp illuminates but does not change intensity, test the control circuit for a short to voltage. If the circuit tests normal, replace the blower motor resistor assembly.
  13. If all circuits test normal, test or replace the blower motor.
scientia non olet · About LEMON Manuals