A/C unit my check gauge light turns on and voltage gauge shows not charging?

1998 JEEP GRAND CHEROKEE LAREDO

130,000 MILES • 4.0L • 6 CYL • 2WD • AUTOMATIC

EDWOOSR667

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hello, i have the vehicle listed above Grand Cherokee Laredo. So, what's going on is, when i turn on my A/C unit my check gauge light comes on plus i get a warning buzzer, and my voltage gauge shows not charging, with an external voltmeter in line voltage shows 0 when i turn the A/C unit off and bring RPMs up to 2,000, voltmeter shows charging at 13. volts again
Any idea what is going on?
Thanks

Jul 27, 2022 at 5:08 PM

SQM

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6,383 POSTS

Hello,

It sounds like the alternator is not performing under load.
To figure out if it is indeed a bad alternator, you will have to remove it and have it bench tested. Most auto parts stores have bench testers for alternators.

Here is a helpful guide:

https://www.2carpros.com/articles/how-to-check-a-car-alternator

I have attached the alternator replacement procedure below for your reference.

Let me know of any questions.
Thank you.

Images (Click to enlarge)

Jul 27, 2022 at 8:15 PM

EDWOOSR667

MEMBER
23 POSTS

thanks for the info. i plain to go and have it checked out.

Jul 27, 2022 at 8:47 PM

SQM

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6,383 POSTS

Sounds good, let me know how it goes.

Jul 28, 2022 at 8:42 PM