• | 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 | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
Blower Motor Control - Low Speed | 2 | 2 | 1 | -- |
Blower Motor Control - High Speed | 2 | 2 | 1 | -- |
Blower Motor Ground | -- | 2 | -- | -- |
1. Blower Motor On at All Times 2. Blower Motor Inoperative |
Low speed is air flowing through the center console ducts being pushed by the front blower motor. Medium speed is controlled by the auxiliary HVAC control module using 1 resistor in series with the blower motor. High speed is also controlled by the auxiliary HVAC control module it applies battery voltage straight to the auxiliary blower motor.
Control Module References for scan tool information
Ignition ON, mode selector set to Vent, command the blower motor from MED to HIGH by changing the blower motor switch positions, the blower motor should activate and operate from medium to high when changing between the commanded states.
⇒ | If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the auxiliary HVAC control module. |
⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
⇒ | If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the auxiliary HVAC control module. |
⇒ | If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the rear blower resistor. |
⇒ | If the blower motor does not activate, replace the blower motor. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for auxiliary HVAC control module replacement, setup, and programming |