Voltage drop when ac compressor runs - JeepForum.com

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post #1 of 7 Old 05-20-2006, 12:07 PM Thread Starter
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Voltage drop when ac compressor runs

When I put on my A/C my voltage drops a whole bunch. Is this the alternator going out or something else perhaps?

Gots me a 93 cherokee
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post #2 of 7 Old 05-20-2006, 12:51 PM
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if your battery is good it may be a loose (high resistance) ground or positive 12V connection. check them all, if not, look at alt next

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post #3 of 7 Old 05-26-2006, 02:40 AM Thread Starter
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Ok so i did a bit of investigating... Ive discovered that sometimes when i start the engine the belt will squeak... (i think its the belt) and the voltage drops the belt stops sweaking and the voltage goes back up the squeaking is also there when i turn the ac on it will go away if i give it a bit of a rev. The battery is good its about 1yr old optima red top, belt tension appears fine. another note tho is when i turn just the fan on the voltage drops slightly.

Is this a pointing at the alternater or something else?

Gots me a 93 cherokee
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post #4 of 7 Old 05-26-2006, 09:59 AM
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I thought this was normal? The AC Compressor uses quite a bit of currrent I thought, enough to make the voltage gage drop for a second. no?

1999 Cherokee Sport
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post #5 of 7 Old 05-26-2006, 10:50 AM
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if your belt is squeeling you may want to tighten the belt. i had a simular problem a while back.
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post #6 of 7 Old 05-26-2006, 11:16 AM
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Might be totally normal. What used to happen with my 98 XJ is that when the clutch on the AC compressor engages, so does the electric fan. And the electric fan would draw enough current to cause my headlights to noticeably dim. The AC compressor clutch would stay engaged for roughly 10 seconds and the fan would keep running during this period.

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post #7 of 7 Old 05-26-2006, 11:49 AM
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Your belt is too loose.

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