kutukutu1

iTrader: (5)

Hello everyone,

i just bought another 7. 82 12a stock to the bone. it comes with a/c. the problem i am having is that when my a/c is turned on the car stays running but my battery gets drained. when i turn it off my battery has no charge. if i keep the a/c off i have no issue. btw i searched and all i found is that a/c kills car not battery.
thanks in advance

xXGslseSleeperXx

shuldn't be happening. load test the battery

Directfreak

iTrader: (2)

Is your alternator working properly?

DivinDriver

iTrader: (15)

Throttle opener still installed and working properly? If yes, RPMs should rise at idle when AC is on to offset AC load, & that boosts alt output.

Could also be weak alt, poor connections at alt or ground, or your in-cabin fan could be failing/rubbing & drawing too much current... or all of the above.

Oneiros

could be your alternator failing, possibly a loose alternator belt as well. the alternator is what charges and keeps the battery topped up when the car is running.

could also be your a/c circuit shorting somewhere.

xXGslseSleeperXx

yes the alternator could be failing to but you would see that syptom most likely even with the a/c off and hard starting. had this happen at the shop before and turns ot it was a shorted cell inthe battery but do test alternator and remove all variables like does it happen with the blower motor on w/o a/c.

Twilightoptics

iTrader: (1)

Sounds like a weak alternator (since the stock 12A alt is crap anyways) and the idle bump vacuum pod is not hooked up or not working causing the idle to be even lower when the a/c is on.

I assume the compressor is engaged with the a/c button on?

What does voltage on the gauge read A/C off? A/C on?

What does the voltage read at the battery itself in both cases?

Oneiros

Possible, but not necessarily so. The A/c could be shorting only when activated causing excessive drain, or the alternator could just barely be keeping up the charge but the a/c tips it over.

rwatson5651

iTrader: (5)

I think this is probably your problem....

Nicholas P.

iTrader: (1)

How to Test a Car Alternator



Equipment needed: multi-meter


With the engine on:

• Step 1:

Open your hood and so you have clear access to the car battery. Locate your alternator and check to be sure the alternator belt isn’t loose.

• Step 2:

Turn your multi-meter to the 20 V setting.

• Step 3:

Start the engine. At this point, check to make sure the alternator pulley / belt is spinning properly without slipping.

• Step 4:

There are two ways to test the voltage coming from the alternator. If you have easy access to the alternator without getting your body parts / clothing / etc tangled in the spinning pulley’s, then place the positive multi-meter probe (red) and touch it to the red terminal connector coming out of the alternator. Now take the negative (black) multi-meter probe and touch it to some metal part of your car frame (like a bolt head nearby or even the negative terminal on the car battery). Don’t ground to the alternator itself. That would be potentially bad. You should now be getting a reading on your multi-meter display. If you don’t have good access to your alternator, then you can simple test the alternator by touching the positive multi-meter probe to the positive terminal on your battery and likewise the negative probe to the negative terminal on your battery.

If the alternator is working well, your multi-meter should read somewhere in the vicinity of 14 volts (typically 13.8-14.2). If it is reading excessively higher than 14 volts (greater than 15 volts) it is possible that the voltage regulator on your alternator is faulty or going bad. If it is reading lower than 13-14 volts, there are a number of possibilities as to the reason. First, it is possible that your engine idle speed is too low for the alternator to put out sufficient voltage/power. Try revving up the engine to 2000 RPM or higher and take a reading. If the voltage is still too low, check to be sure all the connectors on your alternator are tight and that the alternator belt is not slipping and is spinning on the pulley correctly. If it is still not putting out sufficient power, then the alternator’s voltage regulator could be bad or the alternator itself may need replaced.

A car alternator needs to be putting out at least 13-14 volts (ideally between 13.8 and 14.2 volts) to effectively charge a 12 volt car battery. If the alternator is putting out too much voltage (15+ volts), it is likely your battery acid will boil over out of the battery. When a battery is near fully charged the alternator will cease to put out sufficient voltage to charge the battery and the reading you will get from the battery probing method will simply be the voltage coming from the battery itself. In this case, you can simply leave your lights on with the car off for ten or fifteen minutes to drain your battery a little bit.

It can also be helpful to test at the battery terminals with the engine off and then turn the car on and test again at the terminals. If your battery is more or less fully charged, it should read at around 12-13 volts with the car off. If you’ve run your car for a long time and while the car is running the voltage reading is in the 13-14 volt range, but then you shut the car off and the battery voltage instantly drops to well below 12 volts (10 volts or under; 9 volts or under in freezing weather conditions), it is likely that your battery needs maintenance or replaced.

Sources:
How to Test Your Car Alternator for Power | eHow.com
How to Test Check a Car Engine Alternator - 2CarPros
http://knol.google.com/k/how-to-tell...rnator-is-bad#
How to Test a Car Alternator

xXGslseSleeperXx

could be that, but mostly everything on the a/c system is a switch and is gunna be grounded one way or another. ie pressure swich, clutch switch, ect. it just depends on what time it needs to be. if the shorts were the cause every thing would be running when not supposed to or fuses would be instanly blown . if the clutch switch was grounded all the time the compressor would never turn off. high resistance on the power wire though is a problem and that can be the source of eccessive amperage drain but is very rare. if its that bad it will blow the fuse first. the blower motor could draw excessive amperage but this would happen either way using it with the a/c on or off while its bieng used. the alternator could just barely be keeping a charge to run the clutch and supply extra voltage to the coils ect. but can eaisly be tested for 14v with a meter while every things on. try it with all the lights on, winshield wipers, accessories, ect. usually if there is 14v than the amperage will be fine to unless there is sumthin wrong with just the rectifier bridge but unlikely. check for high resistance on the wires to the ac cluctch and the alternator wire leading to the battery. the pressure switch you could do too but remeber just the wires( they are switches not sensors)they will read o.L, if it aint the alternator and wiring from it, its gunna be the battery!

kutukutu1

iTrader: (5)

so i tested the original alternator and it was only putting out about 12.7 volts, its the original so i assumed its the alternator itself, so i swapped it with the one on my 84 rx7 and i ran it for a while with the a/c on, turned off the car and it cranked back up. but after a few cranks in the day with the a/c on i see that the voltage reading in the dashboard is getting lower and not staying were it originally was. W/O a/c it reads about 14v, when i turn it on it goes down to about 13v, after about 2 cranks i am at 12v. i am going to replace the belts and raise up the idle a bit because it does come down substantially with a/c on even with the mushroom pot that raises the idle when a/c is on. ill keep you guys posted

thanks