Voltage drop from 14 to 12 when turning A/C (L83 swap)
12-27-2018, 11:30 AM
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Voltage drop from 14 to 12 when turning A/C (L83 swap) hi guys
Before saying anything I have a new alternator + New battery + new compressor
I have a 91 C1500 swapped with an genv l83 engine out of Silverado 2015
I’m facing a problem with my A/C, whenever I turn it on the voltage drops from 14.6 to 12.2 or so, I’ve replaced everything.
please dont say get a bigger alternator because I did have 170 amp alternator.
my A/C is cold, dual fans are working great, one fans starts then after 8 second the other fan kicks to minimize the voltage drop.
There is some thing wrong with the wiring I think what could it be?, and its a variable displacement type.
Before saying anything I have a new alternator + New battery + new compressor
I have a 91 C1500 swapped with an genv l83 engine out of Silverado 2015
I’m facing a problem with my A/C, whenever I turn it on the voltage drops from 14.6 to 12.2 or so, I’ve replaced everything.
please dont say get a bigger alternator because I did have 170 amp alternator.
my A/C is cold, dual fans are working great, one fans starts then after 8 second the other fan kicks to minimize the voltage drop.
There is some thing wrong with the wiring I think what could it be?, and its a variable displacement type.
12-27-2018, 12:01 PM
#2
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Check all your grounds.
12-27-2018, 12:54 PM
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The problem showing at the idling rpm at most, the wire from the alt to the battery is new as well as the alt clip.
the problem is only when i hit the A/C switch, everything else is fine including the fans
12-27-2018, 01:02 PM
#5
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OK, the voltage drops, but at idle w/AC on, does it rise back up? Or flatline at 12v?
12-27-2018, 01:04 PM
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I'm sure you understand there will always be a voltage drop when the a/c system comes on with all the extra loads. It does seem a bit much dropping to 12.2. As I see you have stated it is at idle most. Do you have an underdrive crank pulley?
12-27-2018, 01:11 PM
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12-27-2018, 01:14 PM
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I know about all that, but every my idle becomes rough when the ac is on, lights are dimming and poor performance.
yes sir I have an under drive crank pulley, my A/C compressor has an independent pulley and belt
12-27-2018, 01:14 PM
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I think it's normal for it to drop to 12v under load, as that is what the regulator is set at to keep it there as a minimum. I could be wrong about this.
12-27-2018, 01:17 PM
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It’s not normal for sure, when the A/C engages my light become dim and my idle becomes rough as well as the performance becomes poor
12-27-2018, 01:44 PM
#11
Run a minimum of an 8 GA wire from the alternator to the Battery ……… Ask me how I know...
Ken
Ken
12-27-2018, 03:07 PM
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what is this solenoid fuse you are talking about ?
12-27-2018, 03:09 PM
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12-27-2018, 03:12 PM
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12-27-2018, 07:01 PM
#17
swapping the relay with another is just an easy way to test it even if new but probably not that anyways.
it sounds like the issue might be from the from the rpm drop itself when the a/c engages... if the ecm is controlling the ac it will maintain the correct the idle speed to account for the extra load for this reason. if the a/c is independent of the ecm that may be the problem.
what is the alternator rated for at idle rpm or the rpm when the ac is engaged? usually the rated output is at a higher rpm afaik
what's regulating the alternator output?
another thing you could test is to unplug the fans so they won't turn on with the a/c and see what the alternator voltage does. maybe you're right at the edge of what the alternator puts out at low rpm.
12-27-2018, 08:02 PM
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sorry autocorrect... should have said ac clutch solenoid
swapping the relay with another is just an easy way to test it even if new but probably not that anyways.
it sounds like the issue might be from the from the rpm drop itself when the a/c engages... if the ecm is controlling the ac it will maintain the correct the idle speed to account for the extra load for this reason. if the a/c is independent of the ecm that may be the problem.
what is the alternator rated for at idle rpm or the rpm when the ac is engaged? usually the rated output is at a higher rpm afaik
what's regulating the alternator output?
another thing you could test is to unplug the fans so they won't turn on with the a/c and see what the alternator voltage does. maybe you're right at the edge of what the alternator puts out at low rpm.
swapping the relay with another is just an easy way to test it even if new but probably not that anyways.
it sounds like the issue might be from the from the rpm drop itself when the a/c engages... if the ecm is controlling the ac it will maintain the correct the idle speed to account for the extra load for this reason. if the a/c is independent of the ecm that may be the problem.
what is the alternator rated for at idle rpm or the rpm when the ac is engaged? usually the rated output is at a higher rpm afaik
what's regulating the alternator output?
another thing you could test is to unplug the fans so they won't turn on with the a/c and see what the alternator voltage does. maybe you're right at the edge of what the alternator puts out at low rpm.
I think that’s my problem, I’m not sure if the A/C is connected with the ecm, all I found about the A/C wirings with the ecm is the A/C hi pressure switch ( sensor on the compressor-condenser line) which I already did it, and some thing called the A/C clutch relay control which I still did not connect it with the ecm, is that an important thing to connect? and if I did it will my A/C system is going to be controlled by the ecm?
im not sure about the alternator but I’m using the stock 2015 ones with 170amp, I was using 160 amp alternator then I upgraded it to 170amp and nothing changed.
the stock alternators are doing well on 2015 silverado with all the luxury equipments and accessories so I don’t think there is a problem if I even use much less amp alternator, I don’t have that bunch of accessories in my truck
12-27-2018, 08:47 PM
#19
I think that’s my problem, I’m not sure if the A/C is connected with the ecm, all I found about the A/C wirings with the ecm is the A/C hi pressure switch ( sensor on the compressor-condenser line) which I already did it, and some thing called the A/C clutch relay control which I still did not connect it with the ecm, is that an important thing to connect? and if I did it will my A/C system is going to be controlled by the ecm?
im not sure about the alternator but I’m using the stock 2015 ones with 170amp, I was using 160 amp alternator then I upgraded it to 170amp and nothing changed.
the stock alternators are doing well on 2015 silverado with all the luxury equipments and accessories so I don’t think there is a problem if I even use much less amp alternator, I don’t have that bunch of accessories in my truck
im not sure about the alternator but I’m using the stock 2015 ones with 170amp, I was using 160 amp alternator then I upgraded it to 170amp and nothing changed.
the stock alternators are doing well on 2015 silverado with all the luxury equipments and accessories so I don’t think there is a problem if I even use much less amp alternator, I don’t have that bunch of accessories in my truck
if its the stock alternator it should do fine to keep up with the requirements you have, and it should be regulated by the ecm so i'm wondering if there's something missing that is goofing that up or that it is just idling down too far when the ac engages. i'm not sure what the strategy is for the ecm to change the output voltage.
might check out this thread, might be a band aid for your situation if there isn't a way to keep the rpms up when ac engages.
https://ls1tech.com/forums/conversio...hrow-away.html
another option might be to raise the target idle rpm in the tune to see if that helps any though the tradeoff is having a higher idle speed when not necessarily needed...never know though if it only takes 50-100 rpm might not be noticable and an easy way to solve the problem.
i'd like to know how this turns out so please follow up if you can
Last edited by 350SS; 12-27-2018 at 08:52 PM.
12-27-2018, 11:41 PM
#20
If you rev the engine up to a higher RPM, does the voltage go back up to normal?
Did you swap the throttle plate to a throttle cable?
My gut feel is that it's not the charging system, but rather the low RPM. The charging system can't possibly supply the demand when the engine RPM is too low. So what could be causing the low RPM? You would think with a 2015 engine management that the ECM would increase the idle speed when the A/C comes on.
Maybe the tune has a mistake where the A/C RPM is low.
Did you swap the throttle plate to a throttle cable?
My gut feel is that it's not the charging system, but rather the low RPM. The charging system can't possibly supply the demand when the engine RPM is too low. So what could be causing the low RPM? You would think with a 2015 engine management that the ECM would increase the idle speed when the A/C comes on.
Maybe the tune has a mistake where the A/C RPM is low.