Chevrolet Trax: Blower motor malfunction (C41, C60)

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

Diagnostic Fault Information

Circuit/System Description

The blower motor is supplied voltage any time the ignition is on via a relay controlled by the body control module.

The blower motor switch applies ground 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 per particular speed request:

• Low speed, 3 resistors
• Medium 1 speed, 2 resistors
• Medium 2 speed, 1 resistors

When blower switch is in the Hi speed position, ground is applied directly to the blower motor through the blower switch.

Diagnostic Aids

Prior to motor replacement connect a direct independent B+ and ground to verify operation.

Inspect the motor shaft for rust or other foreign material which may prohibit proper motor operation.

If the motor operates properly please reinstall it, check for Preliminary Information or Technical Service Bulletins.

Reference Information

Schematic Reference

HVAC Schematics (Encore), HVAC Schematics (Trax)

Connector End View Reference

WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - ENCORE WIRING SYSTEMS AND POWER MANAGEMENT - COMPONENT CONNECTOR END VIEWS - INDEX - TRAX

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

1. Ignition ON
2. Verify the blower motor operates in all speed positions

If the blower motor does not operate in any speed position

Refer to Blower Motor Circuit Test

If the blower motor operates in one or more, but not all speed positions

Refer to Blower Motor Switch Circuit Test

If the blower motor is always ON

Refer to Blower Motor Always ON Circuit Test

If the blower motor operates correctly in all speed positions

3. All OK.

Circuit/System Testing

Blower Motor Circuit Test

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the R3 Blower Motor Resistor. It may take up to 10 min for all vehicle systems to power down.
2. Place the blower motor switch in the high speed position.
3. Test for less than 10 ohms between the control circuit terminal D and ground.

If 10 ohms or greater

1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module.
2. Test for greater than 2 ohms between the ground circuit terminal 1 and ground.

• If less than 2 ohms, replace the K33 HVAC Control Module.
• If greater than 2 ohms

3. Test for less than 2 ohms in the ground circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.

If less than 10 ohms

4. Ignition OFF, connect the harness connector at the R3 Blower Motor Resistor and disconnect the harness connector at the M8 Blower Motor.
5. Test for less than 10 ohms between the control circuit terminal 1 and ground.

If 10 ohms or greater

1. Ignition OFF, disconnect the harness connector at the R3 Blower Motor Resistor.
2. Test for less than 2 ohms in the control circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, test or replace the R3 Blower Motor Resistor.

If less than 10 ohms

6. Ignition OFF, disconnect the KR32E Blower Motor Relay.
7. Test for less than 10 ohms between the ground circuit terminal R4-1 and ground.

If 10 ohms or greater

1. Ignition OFF.
2. Test for less than 2 ohms in the ground circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, repair the open/high resistance in the ground connection.

If less than 10 ohms

8. Ignition ON.
9. Verify a test lamp illuminates between the B+ circuit terminal R4-3 and ground.

If the test lamp does not illuminate and the circuit fuse is good

1. Ignition OFF, remove the test lamp.
2. Test for less than 2 ohms in the B+ circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse.

If the test lamp does not illuminate and the circuit fuse is open

1. Ignition OFF, remove the test lamp.
2. Test for infinite resistance between the B+ circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance

3. Test for infinite resistance between the M8 Blower Motor control circuit terminal 2 and ground.

• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance

4. Test the KR32E Blower Motor Relay, refer to Component Testing.

• If the relay tests OK, test or replace the M8 Blower Motor.
• If the relay does not test OK, replace the KR32E Blower Motor Relay.

If the test lamp illuminates

10. Verify a test lamp illuminates between the control circuit terminal R4-2 and the ground circuit terminal R4-1.

If the test lamp does not illuminate

Repair the open/high resistance in the control circuit.

If the test lamp illuminates

11. Connect the harness connector at the M8 Blower Motor.
12. Install a 40 A fused jumper wire between the B+ circuit terminal R4-3 and the control circuit terminal R4-5, ignition ON.
13. Verify the M8 Blower Motor operates.

If the M8 Blower Motor does not operate

1. Ignition OFF, remove the jumper wire and disconnect the harness connector at the M8 Blower Motor.
2. Test for less than 2 ohms in the control circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, test or replace the M8 Blower Motor.

If the M8 Blower Motor operates

14. Refer to Testing for Intermittent Conditions and Poor Connections .

Blower Motor Switch Circuit Test

1. Ignition OFF, disconnect the harness connector at the R3 Blower Motor Resistor.
2. Test for less than 10 ohms between each control circuit terminal listed below and ground with the blower switch in the appropriate position.

• Blower speed 1 terminal E
• Blower speed 2 terminal A
• Blower speed 3 terminal B
• Blower speed 4 terminal D

If 10 ohms or greater

1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module.
2. Test for less than 2 ohms in the control circuit end to end.

• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K33 HVAC Control Module.

If less than 10 ohms

3. Test or replace the R3 Blower Motor Resistor.

Blower Motor Always ON Circuit Test

1. Ignition OFF, disconnect the harness connector at the R3 Blower Motor Resistor.
2. Place the blower motor switch in the OFF position.
3. Test for infinite resistance between each control circuit terminal listed below and ground:

• Blower speed 1 terminal E
• Blower speed 2 terminal A
• Blower speed 3 terminal B
• Blower speed 4 terminal D

If less than infinite resistance

1. Disconnect the X1 harness connector at the K33 HVAC Control Module.
2. Test for infinite resistance between the control circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance, replace the K33 HVAC Control Module.

If infinite resistance

4. Ignition OFF, disconnect the harness connector at the M8 blower motor.
5. Test for infinite resistance between the control circuit terminal 1 and ground.

If less than infinite resistance

Repair the short to ground on the circuit

If infinite resistance

6. Refer to Testing for Intermittent Conditions and Poor Connections .

Component Testing

Relay Test

1. Ignition OFF, disconnect the KR32E Blower Motor Relay.
2. Test for 60-180 ohms between terminals 85 and 86.

If not between 60-180 ohms

Replace the KR32E Blower Motor Relay.

If between 60-180 ohms

3. Test for infinite resistance between the terminals listed below

• 30 and 86
• 30 and 87
• 30 and 85
• 85 and 87

If less than infinite resistance

Replace the KR32E Blower Motor Relay.

If infinite resistance

4. Install a 3 A fused jumper wire between relay terminal 86 and 12 V. Install a jumper wire between relay terminal 85 and ground.
5. Test for less than 2 ohms between terminals 30 and 87.

If 2 ohms or greater

Replace the KR32E Blower Motor Relay.

If less than 2 ohms

6. All OK

Blower Switch

1. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control Module.
2. Test for infinite resistance between the ground terminal 1 and each control terminal with the blower switch in the OFF position.

If less than infinite resistance

Replace the K33 HVAC Control Module.

If infinite resistance

3. Test for less than 2 ohms between the ground terminal 1 and each control terminal with the switch in the appropriate position.

If 2 ohms or greater

Replace the K33 HVAC Control Module.

If less than 2 ohms

4. All OK.

Blower Motor Resistor

1. Ignition OFF, disconnect the harness connector at the R3 Blower Motor Resistor.
2. Test for 2.7-3.3 ohms between terminal C and terminal E.

If not between 2.7-3.3 ohms

Replace the R3 Blower Motor Resistor

If between 2.7-3.3 ohms

3. Test for 1.62-1.98 ohms between terminal C and terminal A.

If not between 1.62-1.98 ohms

Replace the R3 Blower Motor Resistor

If between 1.62-1.98 ohms

4. Test for 0.72-0.88 ohms between terminal C and terminal B.

If not between 0.72-0.88 ohms

Replace the R3 Blower Motor Resistor.

If between 0.72-0.88 ohms

5. Test for 0.36-0.44 ohms between terminal C and terminal D.

If not between 0.36-0.44 ohms

Replace the R3 Blower Motor Resistor.

If between 0.36-0.44 ohms

6. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• HVAC Component Replacement Reference (C60), HVAC Component Replacement Reference (C41)
• Control Module References for HVAC control module replacement, programming and setup

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