92: Charging Problem as Soon as A/C was fixed?

92 xj 4wd 5spd. Guy converted my A/C, charged it with new stuff was working great, as I was sitting in cab enjoying his work, I notice the alt gauge at zero, and then my rig dies, battery is dead. Alternator is fairly recent, should be fine. Guy says nothing he has done could cause this, but he checks fuses and relays, wiggles some wires, charges my battery and away I go, car runs fine the 60 miles to my house. I test it around street a few times, gauge shows around 13 instead of 14, but truck runs good, a/c works fine.

Today I take a 60 mile trip, on way home gauge is showing low juice, hovers just above the 9 on gauge. This is w/o running A/C at all today.

Thoughts? Looks like a mgr PIA to get alt out, what can/should I do before I start blaming my alternator?

Thanks

When in doubt...

Ok. First thing, charge up the battery and have it load tested.

While that is happening, clean both ends of your main cables.

Renew your grounds.

Ok. Fully charged good battery installed. Voltmeter between the battery terminals--static reading should be 12.5 volts. Start the engine, should now read 13.0-15.3 volts depending on ambient temperature.

Post up what you find.

Good luck.

Did he replace the compressor or mess with the belt at all? Just wondering if its just the belt slipping.

My 92 charges sometime then when you shut it off it quits charging. Sometimes it will start charging if you rev it past 4k. took alternator off and checked said it was ok? someone please help

Cosmo1402 said:

My 92 charges sometime then when you shut it off it quits charging. Sometimes it will start charging if you rev it past 4k. took alternator off and checked said it was ok? someone please help

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There is a serious problem with chain parts stores testing the Nippon Denso PCM regulated alternators--they report the alternators as GOOD when they are not.

To make things worse, the instrument panel voltage gauge reads at the end of the loads, so it isn't very accurate. Attach a voltmeter to the battery terminals, static voltage should be 12.5 volts. Start the engine and check the voltage, should be 13.0 to 15.3 volts depending on the ambient temperature.

Post up what you find.

right now it is not charging at all. is this alternator regulated internally? as far as checking them at the stores you are right I hafd to get the only guy I trust in the store to check one I got from the junkyard to get an accurate test. first guy told me it was bad lookin at it. then when i got him to hook it up he said it was bad and hadn't hooked up the wires. then he only hooked up 2 wires and said it was bad. I got pissed came back later when the other guy was there and it checked like 15 or more. maybe 16 so how is this regulated? i was told some of these are regulated by a computer. don't want to buy a high dollar alternator to find out problem is something else. thanks for the respond. If it is regulated by a computer is this a common problem or is the alter5nator a common problem? How can I eliminate the one that is working properly

Cosmo1402 said:

right now it is not charging at all. is this alternator regulated internally?

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The 92 alternator is regulated by the engine computer. Parts stores have a bad habit of either claiming they're all bad so they can sell you a new one, or their tester doesn't apply a load and won't show when they're truly bad. They also won't show a leaky diode that runs your battery down but otherwise charges okay.

Your best bet is to lookup a local shop that rebuilds alternators and have them test it. They can also sell you a good quality rebuilt - not the Chinese crap at the auto stores.

Again same advice as above. Check the wiring and grounds. Any check engine light?

Does run the battery down. will take to alternator shop monday thanks for your help. yes I have a check engine light. what is the correct charging voltage on the machine? I know the guy I helped hook up the test correctly, hooked it up but don't know the quality of the machine, looked impressive.

Went to the alternator rebuild shop. replaced brushes in alternator good to go 15 bucks. thanks all for the help

Cosmo1402 said:

Went to the alternator rebuild shop. replaced brushes in alternator good to go 15 bucks. thanks all for the help

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Excellent!