Control Assembly: Testing and Inspection

The operation of the Circulation door can be viewed by removing the blower motor and looking up into the unit inlet. See Blower Motor Wheel and Assembly replacement for service procedures.
1. Connect the test set vacuum probe to the heater-A/C vacuum supply (Black) hose in the engine compartment. Position the test set gauge so that it can be viewed from the passenger compartment.
2. Start with the Mode control in the Panel position and the Circulation control in the Outside-air position.
3. Move the Circulation control to the Recirculation position (the Circulation door should move into the Recirculation position). After a short pause move the Mode control to the Defrost position (the Circulation door should move to the Outside-air position). The test gauge should return to the calibrated setting of 27 kPa (8in. Hg.) after each selection is made. If the gauge cannot achieve the calibrated setting, the vacuum circuit or a component has a leak.
4. If the gauge achieves the calibrated setting but the door does not move, there is either a pinched vacuum line or a failed actuator.

Locating Vacuum Leaks
1. Connect the test vacuum probe to the vehicles (Black) supply hose. Position the vacuum test gauge so it can be viewed from the passenger compartment.
2. Place the Mode in the Panel position and the Circulation control in the Recirculation position.
3. Remove the instrument panel top cover.
4. Remove the right side upper instrument panel bezel
5. Remove the center vent duct.
6. Remove and block the Supply (Black) vacuum line at the control. The test gauge should return to the calibrated setting of 27 kPa (8 in. Hg). If not, there is a leak in the Supply line.
7. If there is no leak in the Supply line, reconnect it to the Control and remove the Actuator Feed (Red) line from the Control. Block the vacuum connection on the Control from where the line was removed.The test gauge should return to the calibrated setting of 27 kPa (8 in. Hg.). If not, there is a leak in the Control.
8. If there is no leak in the Supply line or the Control, reconnect the Actuator Feed (Red) line to the control. Remove and block the Actuator Feed (Red) line at the Actuator. The test gauge should return to the calibrated setting of 27 kPa (8 in. Hg.). If not there is a leak in the Actuator Feed line.
9. If there is no leak in the Supply line, Control, or the Actuator Feed line, the leak must be in the Actuator itself. Connect the Vacuum hose from the Vacuum Test Gauge directly to the Actuator to verify the leak. The Actuator vacuum port is accessible behind and above the Glove Box.

Locating Pinched Vacuum Lines
The operation of the Circulation door can be viewed by removing the blower motor and looking up into the unit inlet. See Blower Motor Wheel and Assembly Replacement procedures.
1. Connect the test vacuum probe to the vehicles (Black) supply hose. Position the vacuum test gauge so it can be viewed from the passenger compartment.
2. Place the Mode in the Panel position and the Circulation control in the Recirculation position.
3. Remove the right instrument panel top cover.
4. Remove the right side upper instrument panel bezel.
5. Remove the center vent duct.
6. Remove the Supply (Black) vacuum line at the control. The test gauge should drop indicating free flow through the Supply line. If not, there is a blockage in the Supply line.
7. If there is no blockage in the Supply line, reconnect it to the Control. Remove the Actuator Feed (Red) line from the Control. The test gauge should drop indicating free flow through the Supply line and Control. If not the vacuum switches on the Control are not functioning.
8. If there is no blockage in the Supply line or the Control, reconnect the Actuator Feed (Red) line to the control. Remove the Actuator Feed (Red) line at the Actuator. The Actuator vacuum port is accessible behind and above the Glove Box. The test gauge should drop indicating free flow through the supply line, Control, and the Actuator Feed line. If not, there is a blockage in the Actuator Feed line.
9. If there is no blockage in the Supply line, Control, or the Actuator Feed line, the Actuator must have failed.Connect the Vacuum hose from the Vacuum Test Gauge directly to the Actuator to verify the Actuator has failed.