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Mazda 323 Drops Idle With A/C

Q. I own a 1989 Mazda 323. It has a 1.6 liter engine, fuel injected with A/C. When the car is at normal idle speed and I turn on the A/C, the idle speed drops significantly. What I mean is that when I turn on my A/C on my other car (a Toyota) the idle speed increases and stays normal. What should I do to keep the Mazda idle speed normal with the A/C on? The A/C compressor is in good condition.

Best regards,

Mazda 323 Drops Idle With A/C

A. It is possible you have a bad or dirty Bypass Air Control/Idle Speed Control (BAC-ISC) valve.

The BAC valve consists of the air valve, which functions only during cold engine conditions, and the ISC valve which works throughout the entire engine speed range. The valve accomplishes this by regulating the amount of air that is allowed to bypass the throttle plates. As the idle speed varies out of the specified range, the idle speed control valve increases the passage size if the idle speed is too low, or it decreases the passage size if the idle speed is too high.

I would try giving the throttle body a good cleaning before condemning any parts. A dirty BAC-ISC is often the cause of the types of problem you describe.

Additional Information provided courtesy of ALLDATA

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