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Low idle with AC 700 1992

posted by  JoDee on  Thu Mar 29 06:51 CST 2007
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last visit: Sat Mar 31 07:19 CST 2007
[RELATED]

My 1992 740 wagon has very low idle when I turn on the AC. I know that it should be raised when the ac goes on , but I haven't been able to find any info to help.








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    Low idle with AC 700 1992

    posted by  Rludwick on  Sat Mar 31 23:27 CST 2007
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    last visit: Sat Aug 31 16:10 CST 2013
    [RELATED]

    If it has the bosch system, you can get a replacement eprom ( chip ) for the computer that is supposed to take care of that...or you can mess with the idle screw, but the computer is supposed to take care of the idle.
    --
    -------Robert, '93 940t, '90 240 wagon, '84 240 diesel (she's sick) , '80 245 diesel, '86 740 GLE turbo diesel, '92 Ford F350 diesel dually








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    Low idle with AC 700 1992

    posted by  syncro on  Sat Mar 31 14:22 CST 2007
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    last visit: Thu Mar 8 16:34 CST 2007
    [RELATED]

    If it has the Regina/Rex ignition/fuel injection system (square coil pack), the base idle should be between 480-520 RPM. This is with the idle control valve hose clamped off.

    Base idle is set with the throttle plate stop screw. Then adjust the Throttle position switch to this setting and the Idle control valve should compensate for the rest of the idle.

    Most people say that the idle speed should be around 780 rpm. This is not true based on the Volvo Regina green book. It states that idle speed will be slightly above 1000 RPM.

    But, do the easy things first and clean everything. Also, make sure that the TPS is working. There is a procedure in the green book where you can adjust the throttle plate stop screw to compensate for A/C drag. It involves attaching a vaccum gauge to the small diameter hose connection on the top of the throttle. Adjust the throttle screw until you see a negative pressure and then bring it back to zero.

    Always count the turns of the screw so you can bring it back to its original setting if needed.








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    Low idle with AC 700 1992

    posted by  Chris Mullet on  Thu Mar 29 08:41 CST 2007
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    last visit: Fri Oct 24 09:08 CST 2014
    [RELATED]

    It sounds like the idle control valve is not reacting properly. It may need to be cleaned out. Probably cleaning the throttle body at the same time wouldn't be a bad idea.







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