voltage issue with A/C?

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crownvic05

New member
Ok, so im posting this here because CVN is having issues with new post. Maybe someone here can help me resolve this. Its not a marauder but a 2005 crown vic lx sport.
Issue im having is that when driving with A/C off, all works great and normal like it should. When driving with A/C on and I come to a stop at a light, voltage drops from 14 to 13 in one shot and car some surges/hesitates. It rapidly goes back up to 14volts. This happens everytime I come to a stop.


Is this issue related more to compressor problem or something else?
 
crownvic05 said:
Ok, so im posting this here because CVN is having issues with new post. Maybe someone here can help me resolve this. Its not a marauder but a 2005 crown vic lx sport.
Issue im having is that when driving with A/C off, all works great and normal like it should. When driving with A/C on and I come to a stop at a light, voltage drops from 14 to 13 in one shot and car some surges/hesitates. It rapidly goes back up to 14volts. This happens everytime I come to a stop.


Is this issue related more to compressor problem or something else?
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The A/C compressor might be locked up. With the A/C off the compressor clutch free wheels. With the A/C on the clutch is engaged and if the compressor is locked up it might be causing the problem.
 
Sounds like a weak alternator not keeping up with the draw of the A/C. Mine dips to 12 flat with A/C, stereo, lights, and perhaps lower yet with anything else. Been that way for a couple of years and never once failed to start even with my hi torque starter. Mine doesn’t hesitate at all but gives off a neat cam surging idle the more I stress the voltage LOL


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So when in parked and ac on, everything is good. If i put the car in drive with ac on, everything is good. When i put car in reverse with ac on, volt dips from 14.2 to 13 then moves back up slowly. With ac on everytime i hit a red light, volt dips to 13 and slowlyback up to 14. With ac off, none of this happens.

So all of this issue happens with ac on. Only time ac and voltage is fine is when in parked.
 
crownvic05 said:
So when in parked and ac on, everything is good. If i put the car in drive with ac on, everything is good. When i put car in reverse with ac on, volt dips from 14.2 to 13 then moves back up slowly. With ac on everytime i hit a red light, volt dips to 13 and slowlyback up to 14. With ac off, none of this happens.

So all of this issue happens with ac on. Only time ac and voltage is fine is when in parked.
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Car starts? A/C blowing cold? No strange noises? I think you're good. It's a machine - don't let it drive you nuts.
 
There's a function in the PCM that's supposed to goose the RPM slightly when the compressor is commanded on to mitigate the additional load. Try disconnecting the battery for a few minutes and see if that clears anything. Other than that, I'm outta idears.
 
crownvic05 said:
Drives me nuts because this is not how car was running until 2 weeks now. So something is going to happen eventually.
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You may not discover the issue until an obvious failure takes place. Then, it will be easier to diagnose and repair - no need in stressing out about something you really don't have control over at the moment. Just let the situation develop and just kick back with your favorite beverage....:cool4:
 
Invective said:
You may not discover the issue until an obvious failure takes place. Then, it will be easier to diagnose and repair - no need in stressing out about something you really don't have control over at the moment. Just let the situation develop and just kick back with your favorite beverage....:cool4:
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Like at night on the side of the road?

He has plenty of control right now. Diagnosing is typically easier in the comfort of your garage. With tools. [emoji6]


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justbob said:
Like at night on the side of the road?

He has plenty of control right now. Diagnosing is typically easier in the comfort of your garage. With tools. [emoji6]


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Philosophers through the ages have grappled with the age old question: Why do machines sometimes do weird stuff? Their collective conclusion: @$#%&*%&$#@$!
 
Start with upgrading to a new alternator and if it persists then compressor. Then you don't have to worry about those two for a long time. If you see anything along the way that looks concerning address it while you're down there. Good luck
 
+1 justbob ^

I would start with checking battery connections, the connection at the alternator, test the battery, and alternator output.
Where in nj are you? If not too far away I can help with diag in person.
 
Grimrepairman said:
+1 justbob ^

I would start with checking battery connections, the connection at the alternator, test the battery, and alternator output.
Where in nj are you? If not too far away I can help with diag in person.
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work in Hackensack and live in union city.


I believe your like a good hour away.
 
Last edited:
Yeah, about an hour pending traffic.
If you don't get it figured out and want help and an excuse for a drive out to the country pm me and I'll give you my address.
 
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