Obviously it has to do with the A/C compressor, but why it revvs up to 3k is beyond me. My Fronty only goes up ~300 rpm when the compressor kicks in...
>
> Hi any idea why whenever the a/c is turned on the rpm races up to around
> 3,000? This is on a 1985 and only does it when the a/c is on. Thanks for
> helping, ben
> snipped-for-privacy@bmi.net
>
>
yup, this feature is called automatic "idle-up". if this feature wasn't there, the significant extra load from the compressor would often cause the engine to stall, due to a reduction in rpm.
your idle-up is out of adjustment. that model may use a vacuum type of idle-up. look for the appropriate adjustment screw. the correct adjustment would increase engine rpm only enough to offset the extra load from the compressor.
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