Air Delivery Improper - Auxiliary
Air Delivery Improper - Auxiliary
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview)provides an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
The auxiliary mode actuator is a 3-wire bi-directional electric motor. Ignition 3 voltage, ground and control circuits enable the actuator to operate. The control circuit uses a 0-12 volts linear-ramped signal to command the actuator movement. The 0 and 12-volt control values represent the opposite limits of the actuator range of motion. The values in between 0 and 12 volts correspond to the positions between the limits.
When the auxiliary HVAC control assembly sets a commanded, or targeted, value, the control signal is set to a value between 0-12 volts. The actuator shaft rotates until the commanded position is reached. The auxiliary HVAC control assembly will maintain the control value until a new commanded value is needed.
Diagnostic Aids
Inspect the auxiliary mode door and the auxiliary mode actuator for the following conditions:
* A misaligned auxiliary mode actuator.
* Broken or binding linkages or auxiliary mode door.
* An obstruction that prevents the auxiliary mode door from operating within its full range of motion.
* Missing seals to the auxiliary mode door.
* Misaligned seals to the auxiliary mode door.
Reference Information
Schematic Reference
HVAC Schematics (HVAC - Automatic)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
* Air Temperature Description and Operation (Air Temperature Description and Operation)
* Air Delivery Description and Operation (Air Delivery Description and Operation)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Ignition ON, engine running, place the auxiliary blower motor switch at the maximum speed position and the front mode switch in the vent or panel position.
2. Press the auxiliary mode control switch from the upper position to the lower position. The auxiliary mode actuator should follow the commanded states.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the auxiliary mode actuator.
2. Test for less than 1.0 ohm between the auxiliary mode actuator ground circuit terminal 3 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 auxiliary mode actuator ignition circuit terminal 1 and ground.
• If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, replace the auxiliary mode actuator.
4. Install a DMM between the control circuit terminal 2 and ground. Command the actuator in each direction. Voltage on the control circuit should change from 0 volts when commanding the actuator in one direction to 12 volts in the other direction.
• If the voltage does not change as specified, replace the HVAC control module.
5. If all circuits test normal, test or replace the auxiliary mode actuator.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Mode Actuator Replacement - Console (Mode Actuator Replacement - Console)
* Control Module References (Programming and Relearning) for auxiliary HVAC control module replacement, setup, and programming