Control Assembly: Testing and Inspection
VACUUM CONTROL SYSTEMAdjust Vacuum Test Bleed Valve:
Heater-A/C Vacuum System Diagnosis Part 1:
Heater-A/C Vacuum System Diagnosis Part 2:
Use an adjustable Vacuum Test Set (Special Tool C-3707-B or equivalent) and a suitable vacuum pump to test the heater-A/C vacuum control system. With a finger placed over the end of the Vacuum Test Probe, adjust the bleed valve on the Vacuum Test Gauge to obtain a vacuum of exactly 27 kPa (8 in. Hg.). Release and block the end of the Vacuum Test Probe several times to verify that the vacuum reading returns to the exact 27 kPa (8 in. Hg.) setting. Otherwise, a false reading will be obtained during testing.
A/C-HEATER CONTROLS
NOTE: The operation of the recirculation-air door can be viewed by removing the blower motor and looking up into the HVAC housing.
1. Connect the Vacuum Test Probe to the vehicle vacuum supply (black) line. Position the Vacuum Test Gauge so it can be viewed from the passenger compartment.
2. Start with the mode control in the Panel position and the recirculation control in the Outside-air position.
3. Move the recirculation control to the Recirculation position (the recirculation-air door should move to the Recirculation position). After a short pause move the mode control to the Defrost position (the recirculation-air door should move to the Outside-air position). The Vacuum Test Gauge should return to the calibrated setting of 27 kPa (8 in. Hg.) after each selection is made. If the Vacuum Test Gauge cannot achieve the calibrated setting, the vacuum circuit or a component has a vacuum leak.
4. If the Vacuum Test Gauge achieves the calibrated setting but the recirculation-air door does not move, there is either a pinched vacuum line or a failed recirculation door actuator.
LOCATING VACUUM LEAKS
1. Connect the Vacuum Test Probe to the vehicle vacuum supply (black) line. Position the Vacuum Test Gauge so it can be viewed from the passenger compartment.
2. Place the mode control in the Panel position and the recirculation control in the Recirculation position.
3. Remove the center instrument panel bezel.
4. Remove the center vent duct.
5. Remove and block the vehicle vacuum supply (black) line at the A/C-heater control. The Vacuum Test Gauge should return to the calibrated setting of 27 kPa (8 in. Hg). If not, there is a leak in the vacuum supply line.
6. If there is no leak in the vacuum supply (black) line, reconnect it to the A/C-heater control and remove the actuator vacuum feed (red) line from the A/C-heater control. Block the vacuum connection on the A/C-heater control from where the line was removed. The Vacuum Test Gauge should return to the calibrated setting of 27 kPa (8 in. Hg.). If not, there is a leak in the A/C-heater control.
NOTE: The vacuum port for the recirculation door actuator is accessible from behind the glove box.
7. If there is no leak in the vacuum supply (black) line or the A/C-heater control, reconnect the actuator vacuum feed (red) line to the A/C-heater control. Remove and block the actuator vacuum feed line at the recirculation door actuator. The Vacuum Test Gauge should return to the calibrated setting of 27 kPa (8 in. Hg.). If not there is a leak in the actuator vacuum feed line.
8. If there is no leak in the vacuum supply (black) line, A/C-heater control, or the actuator vacuum feed (red) line, the vacuum leak must be in the recirculation door actuator itself. Connect the Vacuum Test Probe directly to the recirculation door actuator to verify the leak.
LOCATING PINCHED VACUUM LINES
NOTE: The operation of the recirculation-air door can be viewed by removing the blower motor and looking up into the HVAC housing.
1. Connect the Vacuum Test Probe to the vehicle vacuum supply (black) line. Position the Vacuum Test Gauge so it can be viewed from the passenger compartment.
2. Place the mode control in the Panel position and the recirculation control in the Recirculation position.
3. Remove the center instrument panel bezel.
4. Remove the center vent duct.
5. Disconnect the vacuum supply (black) line from the A/C-heater control. The Vacuum Test Gauge should drop, indicating free flow through the supply line. If not, there is a blockage in the supply line.
6. If there is no blockage in the vacuum supply (black) line, reconnect it to the A/C-heater control. Remove the actuator vacuum feed (red) line from the A/C-heater control. The Vacuum Test Gauge should drop indicating free flow through the supply line and A/C-heater control. If not, the vacuum switch on the A/C-heater control is not functioning.
NOTE: The vacuum port for the recirculation door actuator is accessible from behind the glove box.
7. If there is no blockage in the vacuum supply (black) line or the A/C-heater control, reconnect the actuator vacuum feed (red) line to the A/C-heater control. Disconnect the actuator vacuum feed line from the recirculation door actuator. The Vacuum Test Gauge should drop indicating free flow through the vacuum supply line, A/C-heater control, and the actuator vacuum feed line. If not, there is a blockage in the actuator vacuum feed line.
8. If there is no blockage in the vacuum supply (black) line, A/C-heater control, or the actuator vacuum feed (red) line, the recirculation door actuator may have failed. Connect the Vacuum Test Probe directly to the recirculation door actuator to verify if it has failed. If the a recirculation door actuator is OK, then recirculation-air door is binding. Repair the recirculation-air door as necessary.