The mode actuator is a 2-wire bi-directional electric motor. There are 2 control circuits that enable the actuator to operate. The control circuits use either a 0 or 12-volt value to coordinate the actuator movement. When the actuator is at rest, both control circuits have a value of 0 volts. In order to move the actuator, the HVAC control module grounds one of the control circuits while providing the other with 12 volts. The HVAC control module reverses the polarity of the control circuits to move the actuator in the opposite direction.

Inspect the mode door and the mode actuator for the following conditions:

Schematic Reference

HVAC Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for Scan Tool Information

1. Ignition ON, place the blower motor switch in the High speed position.

⇒	If the blower motor is inoperative, refer to Blower Motor Malfunction .

2. Observe the air flow while rotating the mode control switch through the vent position, bi-level position, floor position and defrost position. The air flow should follow the commanded states and flow from the vent, floor, and defrost outlets.

1. Ignition OFF, disconnect the harness connector at the mode actuator.
2. Ignition ON, connect a test lamp between the control circuit terminal A and control circuit terminal B. Command the actuator in each direction. The test lamp should briefly illuminate when commanding the actuator in one direction to the other direction.

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

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

3. If all circuits test normal, test or replace the mode actuator.

1. Install a 10-amp fused jumper wire between the control terminal A and 12 volts. Momentarily install a jumper wire between the control terminal B and ground. The mode actuator shaft should rotate.

⇒	If the function does not perform as specified, replace the mode actuator.

2. Reverse the jumper wires; the mode actuator shaft should rotate.

⇒	If the function does not perform as specified, replace the mode actuator.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.