Intermittent A/C issue related to voltmeter gage change?

KATfishing

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2008 Yukon Denali, 6.2L, 181K miles. Original A/C components and alternator. Newer battery.
On hot days my A/C has intermittently quit working while driving. When it happens I always notice the volt gage displaying its lower level as seen in second pic. In first pic (above 14), the AC is usually working. When it quits working, I can shut off the vehicle at my next stop and it always "resets" and is working again. Sometimes, it'll begin working again while driving and during those times I notice the gage has returned to 14+. I am not a mechanic, but I've learned a lot from this forum, sometimes just by asking a few simple questions that help point me in the right direction as to whether its a DIY job or take it to the professionals. Think the gage correlation is purely coincidental? Or, might this be related to the electrical system... perhaps alternator? The alternator is original, but there haven't been any typical signs of it failing (i.e. dimming dash lights/headlights, or error lights). Vehicle starts strong every time. Or is it more likely a failing compressor, or something else in the AC system? So far, it keeps coming back ice cold, but when it goes out it's completely warm. My snowflake button to activate the AC stays fully lit whether it's working or not. Thanks for any thoughts.


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Doubeleive

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well supposedly when the ac is going the voltage is supposed to in a charge mode, the RVC (regulated voltage control) will not charge the battery if it detects there is a enough charge to run everything without needing additional power, ac of course is a big drain so what you are seeing is normal voltage wise.
you may want to have the ac system checked to be sure it is fully charged for starters and go from there. if the r12 or whatever they use now is low it can make the system be intermittent, but so can some other things but I would start with the ac charge test first.
 

Foggy

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The electric fans take quite a bit of power... So maybe your fans are weak or
your alternator is not good enough to keep the fans going at the proper speeds
 

Geotrash

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Next time it happens, before you shut the car off, pop the hood and take a look at the air conditioning compressor. What you’re looking for is whether or not the clutch is engaging the compressor or not. I’m guessing that your air conditioning compressor clutch is starting to fail requiring more voltage than is available when the alternator is in no charge mode to function.
 

BG1988

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2008 Yukon Denali, 6.2L, 181K miles. Original A/C components and alternator. Newer battery.
On hot days my A/C has intermittently quit working while driving. When it happens I always notice the volt gage displaying its lower level as seen in second pic. In first pic (above 14), the AC is usually working. When it quits working, I can shut off the vehicle at my next stop and it always "resets" and is working again. Sometimes, it'll begin working again while driving and during those times I notice the gage has returned to 14+. I am not a mechanic, but I've learned a lot from this forum, sometimes just by asking a few simple questions that help point me in the right direction as to whether its a DIY job or take it to the professionals. Think the gage correlation is purely coincidental? Or, might this be related to the electrical system... perhaps alternator? The alternator is original, but there haven't been any typical signs of it failing (i.e. dimming dash lights/headlights, or error lights). Vehicle starts strong every time. Or is it more likely a failing compressor, or something else in the AC system? So far, it keeps coming back ice cold, but when it goes out it's completely warm. My snowflake button to activate the AC stays fully lit whether it's working or not. Thanks for any thoughts.
the current sensor could be bad this is part of the charging circuit..


if it is the clutch just replace the clutch don't replace the whole compressor


it would be hard to trust a remanufatured or new one as now days the quality is poor
 

Denali Deen

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My a/c has been doing the same for a couple of years and have not been able to track it down. I replaced the compressor and it seemed better for a short time then back to the same thing. Then did the expansion tank and was a little better but again back to the same thing. Over the winter my alternator started acting up getting a discharge warning while driving. I finally put a new alternator in and a/c has not been cutting out like it used to. Not sure that it is officially fixed but has been better after the alternator
 

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