# a/c compressor draining all my battery power?



## Pieandcake123 (Aug 18, 2013)

Hi, i got a 95 sentra ga16 engine and i fixed the a/c a few days ago. now i got this problem= When i turn on the AC starts to drain my battery power down to 12.10v(engine on) when i turn it off it goes back up to 13.8-14volts. i turn ON the blower to max with compressor OFF and its 13.8 volts(normal) So i think its the compressor magnetic coil, i jumped the relay just to turn ON the compressor ALONE(no blowers nothing), when its ON it drops the voltage to 12.10 or less.

I think is the compressor magnetic coil but im not sure.

What you guys think it is? help a noob fix his first car.


----------



## jdg (Aug 27, 2009)

And how far does the idle drop with the A/C on?
A/C compressor = large-ish load
Blower motor = not large-ish load


----------



## Pieandcake123 (Aug 18, 2013)

jdg said:


> And how far does the idle drop with the A/C on?
> A/C compressor = large-ish load
> Blower motor = not large-ish load


the car is always on 900 rpm(idk why) and when i turn the ac on it drops to 800 rpm then goes back up to 900.


----------



## jdg (Aug 27, 2009)

Try another handful of loads and see what happens, like headlights/blower/blinker/brakes/radio/etc/etc.
Could be that the alternator can support the electrical load of the blower, but not the A/C compressor, which I would think is a fair amount higher.
And, another thing, try it at a higher RPM.
If the voltage doesn't drop off at a higher RPM, I wouldn't worry about it.
If the voltage does still drop off, I would think that either the alternator is on the way out, maybe the belt is slipping, etc...


----------



## Pieandcake123 (Aug 18, 2013)

jdg said:


> Try another handful of loads and see what happens, like headlights/blower/blinker/brakes/radio/etc/etc.
> Could be that the alternator can support the electrical load of the blower, but not the A/C compressor, which I would think is a fair amount higher.
> And, another thing, try it at a higher RPM.
> If the voltage doesn't drop off at a higher RPM, I wouldn't worry about it.
> If the voltage does still drop off, I would think that either the alternator is on the way out, maybe the belt is slipping, etc...


okay i will try doing that. and the alt and battery are brand new. just installed them 3 days ago.


----------



## worthirt (May 21, 2013)

was the alternator from autozone or someplace like that? Nissan's don't take kindly to the big box store alternators and starters.


----------



## Pieandcake123 (Aug 18, 2013)

worthirt said:


> was the alternator from autozone or someplace like that? Nissan's don't take kindly to the big box store alternators and starters.


it was from advance auto parts.


----------



## Pieandcake123 (Aug 18, 2013)

ive done some testing 
Results:

warm engine.
Radiator fans ON only 13.03v @ 600rpm
Radiator fans OFF 13.44v @ 600rpm
Everything ON Blower max,headlights,taillights,emergency blinkers,window wipers and radio 12.30v @ 700rpm

looks like the alternator is weak. a piece of shit.


----------



## worthirt (May 21, 2013)

hate to say it, but get a nissan one; they are a little more expensive, but are built well.


----------



## Pieandcake123 (Aug 18, 2013)

worthirt said:


> hate to say it, but get a nissan one; they are a little more expensive, but are built well.


yeah youre right..


----------



## jdg (Aug 27, 2009)

I don't think so...depends on what the spec for that particular engine/alternator combo says.
Back in the day, every vehicle out there would lose a bit of voltage at low idle when electrically loaded down.
Not saying every one of today's vehicles are the same, not saying they're not.
Point is, if you bring up the rpm's just a little bit while the electrical system is under a load, does the voltage come up to regulation or not?
If it was my vehicle, I'd let it go. After all, you don't spend all day idling with everything turned on.
And to top that off, you mentioned you also replaced the battery.
Who's to say that thing isn't crap rather than the alternator?


----------



## Pieandcake123 (Aug 18, 2013)

jdg said:


> I don't think so...depends on what the spec for that particular engine/alternator combo says.
> Back in the day, every vehicle out there would lose a bit of voltage at low idle when electrically loaded down.
> Not saying every one of today's vehicles are the same, not saying they're not.
> Point is, if you bring up the rpm's just a little bit while the electrical system is under a load, does the voltage come up to regulation or not?
> ...


its a brand new battery from walmart how can it be crap?

anyways soon im going to replace the compressor to see if it solves the problem.


----------



## worthirt (May 21, 2013)

new batteries may not be new. I say that because after manufacture they will sit on a shelf either in a warehouse or in the store until someone buys them. Sometimes they will go bad from sitting on a shelf too long. That is what jdg may have ment when he said that the battery was "crap".


----------



## EvilPotato (Sep 6, 2005)

my voltage drops below 12v when at idle and a/c and headlights are on due the underdrive crank pulley. i dont think it will do any damage to anything since the battery is at least 7 years old and counting. like previously suggested, monitor the voltage during driving conditions. also when the engine is warmed up and you come to a stop, under hood temp rises and the battery and alternator get hot and lose some efficiency a bit. but 12.3v under full load, with everything you can throw at it, at idle, seems ok to me.


----------



## azkicker0027 (May 31, 2002)

also check the most obvious items such as the positive terminal, cable, negative terminal, cable, body ground, and engine ground. Also make sure the belt is correctly tensioned and the pulleys are not binding.


----------



## Pieandcake123 (Aug 18, 2013)

azkicker0027 said:


> also check the most obvious items such as the positive terminal, cable, negative terminal, cable, body ground, and engine ground. Also make sure the belt is correctly tensioned and the pulleys are not binding.


where can i find all these grounds? pictures please?


----------



## Pieandcake123 (Aug 18, 2013)

bump ignore this


----------



## IanH (Feb 11, 2003)

I dont think you have anything wrong.
You can measure your amp draw with an amp meter and compare to the spec.
I have both regular and inductance types i use for checking something like this.

Alternators do not put out much in the way of amps at low rpm, try turning the idle speed up, from what I remember both my GA16 and SR20 had higher idle with AC on, about 1000 rpm...You should have some kind of idle up...
It been a while since i had these so you will have to check the specs.


----------



## Pieandcake123 (Aug 18, 2013)

IanH said:


> I dont think you have anything wrong.
> You can measure your amp draw with an amp meter and compare to the spec.
> I have both regular and inductance types i use for checking something like this.
> 
> ...


its on 1,000 rpm already always was


----------



## IanH (Feb 11, 2003)

Then i suggest you measure the current draw.


----------



## jdg (Aug 27, 2009)

Pieandcake123 said:


> its on 1,000 rpm already always was


Refer back to post #3 and post #8.

Somebody needs to get a story straight.


----------



## VerdellMelo (Aug 10, 2013)

Pieandcake123 said:


> the car is always on 900 rpm(idk why) and when i turn the ac on it drops to 800 rpm then goes back up to 900.


you need to djust the race of the cars, i am sure that would work well , and would also eliminate the problem of yours.


----------

