Engine Air Temperature Control System (Opel Vectra B)

System (single point injection) is controlled by a temperature-sensitive vacuum switch mounted in the throttle body housing. When the air temperature passing through the throttle body is below 35°C, the vacuum switch is opened, allowing the vacuum in the intake manifold to act on the air diaphragm of the temperature control valve at the base of the air cleaner housing. The vacuum lifts the diaphragm and moves the air intake flap valve, causing air to enter the engine that has been heated near the exhaust manifold.

As the temperature of the incoming air increases due to heating by the exhaust manifold, a wax capsule in the vacuum switch closes the switch, cutting off the vacuum to the incoming air temperature control valve. Since the vacuum is cut off, the air intake flap moves and closes the control valve at a temperature of about 40°C. This allows only cool air from the front of the car to enter the engine.

Examination

Cool the engine, then separate the intake duct from the front of the air cleaner housing. The flap valve of the control valve should be blocking the flow of hot air. Start the engine. The flap should immediately rise and block the flow of cold air and, after the engine has warmed up, should move to open the flow of only cold air.

To test the vacuum switch, disconnect the vacuum tube from the control valve and plug the tube with your finger. When the engine is cold, there should be a vacuum in the tube, and after the engine has warmed up to normal operating temperature, there should be no vacuum.

To check the operation of the intake air temperature control valve, separate the intake duct from the air cleaner housing. The flap valve should close off the hot air flow into the engine. Disconnect the vacuum pipe and create a vacuum in it. This should move the flap and close off the cold air flow into the engine.