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Large drop in idle rpm when AC is turned on 900 93

posted by  someone claiming to be Richard Swartz on  Mon Dec 11 04:33 CST 2000 [RELATED]

Hello and help,

93 940t

Problem: When the ac is engaged the idle drops to about 450-500 rpms and does not return to normal.

I have set and reset the base idle. I have replaced the idle air valve as well as the TPS. When the AC is off the car runs fine. When the AC is on It often feels as it wilol stall but never does.

I have 2 other volvos. each idle at 750-800 rpms, when the ac is engaged the idle rises to 900-920 rpms.

Does anyone know why the 940 T will not do the same?

thanks,

Rich







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    Re: Large drop in idle rpm when AC is turned on 900 93

    posted by  someone claiming to be paul on  Thu Dec 14 13:18 CST 2000 [RELATED]

    On your model, idle speed is controlled by the fuel ecu / IACV. There may be a signal to the ECU when the AC is on (check a wiring diagram). If this is the case - check that this circuit is functional. I assume that the IACV operates correctly (it may have been replaced - but is the wiring OK??). Is the TPS signal to the ECU correct (adjustment, and wiring). I would be looking at wiring for dirty connections.

    Hope this helps.







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    Re: Large drop in idle rpm when AC is turned on 900 93

    posted by  someone claiming to be keefus on  Thu Dec 14 08:21 CST 2000 [RELATED]

    There is supposed to be some sort of switch or solenoid that kicks up idle speed when A/C is engaged. Check your fuses, and check the 700/900 FAQ for more info.






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