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Erratic rpms

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Old 06-21-2018, 03:32 PM
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Default Erratic rpms
2014 JK, standard trans. While idling with the AC compressor running the rpms fluctuate erratically between 2000-5500. As soon as I turn the AC or defroster off the issue goes away. Any ideas as to which sensor / sensors it may be?
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Old 06-21-2018, 05:02 PM
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Any chance your battery can be failing due to the current draw with the ac on? When my battery went bad my rpm gage as well as other lights did erratic things.
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Old 06-21-2018, 05:22 PM
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Unfortunately no. I just replaced it a few months ago.
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Old 06-21-2018, 08:29 PM
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Alternator maybe? I'd give that a check. Check continuity with the Jeep running.
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Old 06-22-2018, 08:27 AM
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Originally Posted by scottray119
Unfortunately no. I just replaced it a few months ago.
Id doublecheck that your battery connections are tight.
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Old 06-22-2018, 08:36 AM
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Originally Posted by rob_engineer
Id doublecheck that your battery connections are tight.
Also just give the battery a check anyways. I bought a new one in September...and it randomly went bad last week.
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Old 06-22-2018, 07:20 PM
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Originally Posted by scottray119
2014 JK, standard trans. While idling with the AC compressor running the rpms fluctuate erratically between 2000-5500. As soon as I turn the AC or defroster off the issue goes away. Any ideas as to which sensor / sensors it may be?
2000 to 5500 RPM is pretty high. Is the A/C putting out cold air and seems normal? What's it like driving with A/C on, does it seem to hunt or lurch, any noise? What happens on the tach when it's rolling above ~25 MPH with A/C on, then put the clutch in and coast?

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Old 06-23-2018, 03:01 AM
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Originally Posted by Mr.T
2000 to 5500 RPM is pretty high. Is the A/C putting out cold air and seems normal? What's it like driving with A/C on, does it seem to hunt or lurch, any noise? What happens on the tach when it's rolling above ~25 MPH with A/C on, then put the clutch in and coast?

AC works fine. No noise. RPMs rise and fall erratically. Going to test the alternator today now that I have a day off to spend working on it
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