Choke Control System: Operation
When engine coolant temperature is less than 59°F (15°C), wax thermovalve is open, allowing manifold vacuum to bleed off from outer choke diaphragm chamber into air cleaner. See Fig 1 and Fig 2 . This causes internal choke opener diaphragm spring tension to force choke valve closed. As coolant temperature increases, amount of vacuum bled into air cleaner is reduced and choke valve is gradually opened.
The cranking leak system is designed to bleed vacuum from the inner choke opener diaphragm during cranking. The cranking leak solenoid is energized by the ignition switch when switch is in the "START" position. Start signal passes through ECU on Accord models before activating solenoid. When the solenoid is energized, vacuum is bled off through solenoid and not applied to the inner choke opener diaphragm. This keeps choke valve fully closed during cranking. When engine is started (ignition switch in "RUN" position), the solenoid is de-energized and full manifold vacuum is applied to the inner choke diaphragm. This will allow choke to open a fixed amount.