Accord 1985-89 and Prelude 1986-89
1. With the engine off, slowly open the throttle until the damper rod rises to the stop.
2. Release the throttle valve and time the time until the throttle valve does not touch the stop screw. This time should be less than two seconds.
3. If this time is more than two seconds, replace the damper control valve.
4. If the traction does not function - check the feedback or clogging of the control valve or vacuum line. If everything is OK - replace the air damper.
Accord 1987-89
1. Check the vacuum line for leaks, blockages or accidentally disconnected hoses.
2. Disconnect vacuum hose No.6 from the air damper diaphragm and connect a hand pump with a pressure gauge to the free end of the hose.
3. Start the engine.
4. Increase engine speed to 3500 rpm. The pressure gauge should show vacuum.
5. If there is no vacuum, check the vacuum pipe on the throttle.
6. Release the throttle. The vacuum should slowly disappear.
7. If the vacuum persists or disappears quickly, replace the damper check valve.
8. Connect the vacuum pump to the damper diaphragm.
9. Apply vacuum and verify that the rod has moved and the vacuum is held.
10. If vacuum does not hold or rod does not move, replace damper diaphragm.
[Information obtained from this source HONDABOOK.ru]