Spark

Blower Motor Malfunction

The blower motor control module is an interface between the HVAC control and the blower motor. The blower motor speed control, battery positive and ground circuits enable the control module to operate. The HVAC control provides a variable voltage to the blower motor control module to request the selected blower speed. The blower motor control module provides a pulse width modulation (PWM) signal to the blower motor in order to control the blower motor speed.

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Automatic HVAC Description and Operation

Electrical Information Reference

1. Ignition OFF, disconnect the harness connector at the K8 Blower Motor Control Module.
2. Test for less than 1.0 Ω between the ground circuit terminal 7 X1 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 6 X1 and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse (HVAC BLWR 25A) in the underhood fuse block is open, test all components connected to the B+ circuit and replace as necessary.

4. Ignition OFF, disconnect the X1 harness connector at the K33 HVAC Control.
5. Ignition ON, test for less than 0.3 V between the control circuit terminal 3 X1 at the K8 Blower Motor Control Module harness connector and ground.

⇒	If greater than the specified range, test the control circuit for a short to voltage.

6. Ignition OFF, test for infinite resistance between the control circuit terminal 3 X1 at the K8 Blower Motor Control Module harness connector and ground.

⇒	If less than the specified range, test the control circuit for a short to ground.

7. Test for less than 5 Ω between the K33 HVAC control circuit terminal 6 X1 and control circuit terminal 3 X1 at the K8 Blower Motor Control Module harness connector.

⇒	If greater than the specified value, test the control circuit for an open/high resistance.

8. Connect the X1 harness connector at the K33 HVAC Control.
9. Ignition ON, connect a DMM between the control circuit terminal 2 X1 at the K8 Blower Motor Control Module harness connector and ground.
10. Cycle the blower motor from OFF to HIGH. The voltage should increase while changing between the commanded states.

⇒	If voltage remains greater than 11.5 V while changing between the commanded states, test the control circuit for a short circuit to voltage. If the circuit test normal, replace the K33 HVAC Control.

⇒	If voltage remains less than 1.0 V while changing between the commanded states, test the control circuit for a short circuit to ground or an open/high resistance. If the circuit tests normal, replace the K33 HVAC Control.

⇒	If voltage is between 1.0--11.5 V and does not increase when changing between the commanded states, replace the K33 HVAC Control.

11. Ignition OFF, reconnect the X1 harness connector at the K8 Blower Motor Control Module and disconnect the harness connector at the M8 Blower Motor.
12. Ignition ON, verify that a test lamp illuminates between the M8 Blower Motor B+ circuit terminal 1 and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K8 Blower Motor Control Module.

13. Connect a test lamp between the M8 Blower Motor control circuit terminal 2 and the M8 Blower Motor B+ circuit terminal 1.
14. Turn the blower motor to high speed then to low speed. The test lamp intensity should be bright when in high speed and very dim or off when the blower is on low speed.

⇒	If the test lamp intensity does not vary, test the control circuit for a short circuit to voltage, short circuit to ground, or an open/high resistance. If the circuit tests normal, replace the K8 Blower Motor Control Module.

15. If all circuits test normal, test or replace the M8 Blower Motor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.