Blower Motor Control Module

The blower motor control module is an interface between the HVAC control module and the blower motor. The blower motor speed control, battery positive and ground circuits enable the control module to operate. The HVAC control module provides a pulse width modulation (PWM) signal to the blower motor control module in order to command the blower motor speed. The control processor uses the blower motor ground as a low side control to adjust 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

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, switch the climate control system to the manual setting. Turn the fan speed control knob from the lowest to highest setting. The blower motor speed should change between commanded states.
2. Turn the blower speed control knob to the "O" position. The blower motor should turn OFF.

1. Ignition OFF, disconnect the harness connector at the blower motor control module connector X2.
2. Test for less than 1.0 ohm between the ground circuit connector X2 terminal 5 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 of the blower motor speed control module supply voltage connector X2 terminal 6 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 40-amp) in the underhood fuse block is open, test all components connected to the B+ circuit and replace as necessary.

4. Connect a test lamp between the blower motor speed control circuit connector X2 terminal 3 and the blower motor supply voltage circuit connector X2 terminal 6 of the blower motor control module.
5. Turn the blower motor ON and then OFF. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the HVAC control module.

⇒	If the test lamp is always OFF, test the speed control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the HVAC control module.

6. Ignition OFF, reconnect the harness connector X2 at the blower motor control module.
7. Disconnect the harness connector at the blower motor.
8. Ignition ON, verify that a test lamp illuminates between the blower motor supply voltage circuit terminal A of the blower motor control module and ground.

⇒	If the test lamp does not illuminate, test the blower motor supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the blower motor control module.

9. Connect a test lamp between the blower motor speed circuit terminal B and the blower motor ground circuit terminal A of the blower motor control module.
10. Turn the blower motor on high speed then to low speed. The test lamp intensity should be bright when in high speed and very dim or out when the blower is on low speed.

⇒	If the test lamp intensity is not correct, test the blower motor ground circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the blower motor control module.

11. If all circuits test normal, replace the blower motor.

Blower Motor

1. Ignition OFF, disconnect the harness at the blower motor.
2. Install a 40-amp fused jumper wire between circuit terminal 1 and 12  volts. Install a jumper wire between the low reference circuit terminal 2 and ground. Verify the blower motor activates

⇒	If the blower motor does not activate, replace the blower motor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.