Should I clean a viscous paper type air cleaner filter?

No. The document states it does not require cleaning and should be replaced periodically; brushing or blasting will cause clogging and enrich the carburetor mixture, and should never be done.

What symptoms indicate a problem with the A.T.C. system?

Engine stall or hesitation, increase in fuel consumption, and lack of power. If these occur, check the A.T.C. system before inspecting the carburetor.

What is the correct air control valve position when the engine is cold?

The air control valve is correct if it is in the lower position when the engine is cold; when the engine is started, it should immediately rise.

How do I test the vacuum motor?

Disconnect the vacuum motor inlet vacuum hose, connect another hose to the inlet to apply vacuum, and confirm that the air control valve moves.

How do I check the temperature sensor?

With the engine cold and idling, disconnect the vacuum motor inlet vacuum hose and verify intake vacuum is present at the end of the hose. If vacuum is weak or absent, check hoses for leaks; replace the temperature sensor if the hoses are in good order.

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Nissan Micra A.T.C. Air Cleaner Inspection - Vacuum Motor & Temp Sensor Test

Nissan Automatic Temperature Control (A.T.C.) air cleaner inspection page, EF & EC manual

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Datsun/Nissan EF & EC service page covering ATC air cleaner, vacuum motor and temperature-sensor checks; air control valve is correct when in the lower position.

AI caption June 2005 · Photo 107 of 412

This is a page (EF & EC-7) from a Nissan factory service manual covering inspection of the Automatic Temperature Control (A.T.C.) air cleaner system on a carbureted engine. It explains that the viscous paper air cleaner filter must not be cleaned by brushing or blasting (which causes clogging and carburetor mixture enrichment) and should simply be replaced periodically. It lists symptoms indicating A.T.C. problems—engine stall or hesitation, increased fuel consumption, and lack of power—and instructs checking the A.T.C. system before inspecting the carburetor. A step-by-step inspection procedure covers checking hoses for cracks and distortion, verifying air control valve position when cold (lower position is correct), confirming the valve rises when the engine starts, checking valve movement with engine speed changes, and confirming partial rise as the engine warms up. If problems are found, further tests are given: applying vacuum directly to the vacuum motor to confirm the air control valve moves, and checking the temperature sensor by verifying intake vacuum at the vacuum motor inlet hose while the engine is cold and idling, replacing the sensor if hoses are sound. Two illustrations (SEF328B, SEF329B) show the air cleaner assembly and vacuum test setup.

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Frequently asked questions

Should I clean a viscous paper type air cleaner filter?: No. The document states it does not require cleaning and should be replaced periodically; brushing or blasting will cause clogging and enrich the carburetor mixture, and should never be done.
What symptoms indicate a problem with the A.T.C. system?: Engine stall or hesitation, increase in fuel consumption, and lack of power. If these occur, check the A.T.C. system before inspecting the carburetor.
What is the correct air control valve position when the engine is cold?: The air control valve is correct if it is in the lower position when the engine is cold; when the engine is started, it should immediately rise.
How do I test the vacuum motor?: Disconnect the vacuum motor inlet vacuum hose, connect another hose to the inlet to apply vacuum, and confirm that the air control valve moves.
How do I check the temperature sensor?: With the engine cold and idling, disconnect the vacuum motor inlet vacuum hose and verify intake vacuum is present at the end of the hose. If vacuum is weak or absent, check hoses for leaks; replace the temperature sensor if the hoses are in good order.