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Blower Motor Malfunction

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    • Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

The blower motor switch assembly applies voltage to the blower motor control circuit that corresponds to the selected blower speed. The resistors and the blower motor are in a series circuit. The following list represents the number of resistors in series with the blower motor at each speed:

    • Low speed - 3 resistors
    • Medium 1 speed - 2 resistors
    • Medium 2 speed - 1 resistor

When the operator requests high speed, the blower switch applies voltage to the high speed blower control circuit, directly to the blower motor.

Reference Information

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Manual HVAC Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

Place the blower switch in Low, Medium 1, Medium 2, and High speed positions. The blower motor should operate in each speed position.

⇒If the blower motor does not function properly in each speed position, refer to Blower Motor Malfunction .

Circuit/System Testing

Blower Malfunction

  1. Ignition OFF, disconnect the harness connector at the R3 Blower Motor Resistor.
  2. Ignition ON, while cycling the blower switch between each speed position, verify a test lamp illuminates between the appropriate control circuit terminal listed below and ground:
    3. • Low - Terminal 2
    • Medium 1 - Terminal 4
    • Medium 2 - Terminal 1
    ⇒If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the Heater and Air Conditioning Control.
  3. Reconnect the R3 HVAC Blower Resistor and disconnect the M8 HVAC Blower Motor. Verify a test lamp illuminates between the control circuit terminal 2 and ground when switched to each speed position.
    4. ⇒If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the R3 Blower Resistor.
    ⇒ If the test lamp does illuminate, test the blower motor ground circuit for a short circuit to open/high resistance. If the circuit tests normal, replace the M8 Blower Motor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Heater and Air Conditioning Control Replacement : Right-Hand Drive → Left-Hand Drive
    •  Blower Motor Replacement : Right Hand Drive → Left Hand Drive
    •  Blower Motor Resistor Replacement : Right Hand Drive → Left Hand Drive
   


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