Blower Controller

The blower 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 controller in order to command the blower motor speed. The control processor uses the blower motor ground or low reference 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. Press the fan speed control button from the lowest to highest setting. The blower motor speed should change between commanded states.
2. Press the power button located on the driver's side of the climate control panel to turn the entire climate control system ON or OFF. The blower motor should turn OFF.

1. Ignition OFF, disconnect the X2 harness connector at the blower motor control module.
2. Test for less than 10 ohms between the ground circuit terminal 5 and ground.

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

3. Verify that a test lamp illuminates between the B+ circuit 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.

4. Connect a DMM between the signal circuit terminal 3 and B+.
5. Ignition ON, cycle the blower motor from OFF to HIGH. The voltage should increase while changing between the commanded states.

⇒	If the voltage remains greater than 11.5 volts when changing between the commanded states, test the control circuit for a short to voltage. If the circuits test normal, replace the HVAC control module.

⇒	If the voltage remains greater than 1.5 volts when changing between the commanded states, test the control circuit for a short to ground or an open/high resistance. If the circuits test normal, replace the HVAC control module.

⇒	If the voltage is between 1.0-11.5 volts and does not increase when changing between the commanded states, replace the HVAC control module.

6. Ignition OFF, connect the harness connector at the blower control module. Disconnect the harness connector at the blower motor.
7. Install at test lamp between the high control circuit terminal 1 and ground.
8. Blower motor ON, verify the test lamp illuminates.

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

9. Install a test lamp between the high control circuit terminal 1 and the low control circuit terminal 2.
10. Turn the blower motor ON and cycle between low and high speeds. The test lamp should illuminate and change in intensity as the blower speed is varied.

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

⇒	If the test lamp does not change intensity, test the low control circuit for a short to ground. If the circuit tests normal, test or replace the blower control module.

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

1. Ignition OFF, disconnect the harness at the blower motor.
2. Install a 40A 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.