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Registered
Join Date: Jul 2003
Posts: 18
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possible alternator failure
hey guys,
i recently bought a 320I 1992 bmw (automatic transm.). I had some problems with the A/C, so i ended up changing the compressor and fixing the evaporator. the A/C is great now, but i've noticed that when i do the kickdown, the A/C gives relatively hot air but the engine is running fine. I though it might be the alternator, or the battery. The mechanics said that the alternator needs to be replaced. The reason i'm posting this is that i don't trust this mechanics at all, maybe u can help me troubleshoot.... thanks in advance, enjoy ur bimmers ![]() John |
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Registered
Join Date: Dec 2002
Location: Los Angeles
Posts: 32
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That is normal operation. Our cars (standard and automatic) are equipped with an A/C cutout device that shuts off the compressor under moderate to hard acceleration, to eliminate the power draw of the compressor. It cuts back in while cruising. The alternator will not cause this problem. To check it, simply put a voltmeter across the battery terminals while the car is running, voltage should be approximately 14.0 volts.
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Registered
Join Date: Jul 2003
Posts: 18
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thx for the tip kingnine, I will buy a voltmeter and start investigating myself. I feel that the electricity in the car is low. whenever i put the headlights on, the radio led goes dimmer. if the voltmeter gave me 14, so it must be the battery then. I'll post back as soon as i know something new.
laters, John |
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Join Date: Jul 2003
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hey again,
I have measured the voltage, its 13.5/.6 at the battery with the engine running. is that in the acceptable range? thx, John |
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Administrator
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Yes, that is acceptable. If it drops below 12.6V, the battery is discharging. (What does it read with the engine running and the headlights on?)
If it goes over ~14.5V, the battery is being overcharged. --DD
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Pelican Parts 914 Tech Support A few pics of my car: http://www.pelicanparts.com/gallery/Dave_Darling |
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I have measured the voltage at the battery while running the engine having the headlights + A/C on and it was around 13.2 or somethin.
regards, John |
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Registered
Join Date: May 2003
Location: Slidell, LA
Posts: 101
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Wait a 'sec, if you turn on the headlights, shouldn't the radio lights dim?
That prevents them from being too bright at night. It definately does that on my other (non bmw) cars. I have not noticed on my BMW though. Will check that out, but I think I'm right. David S |
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In the shop at Pelican
Join Date: Aug 2002
Location: Los Angeles, CA
Posts: 10,459
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It's also not a bad idea to turn off the A/C compressor if you plan on accelerating quickly. Takes some of the strain off the engine.
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Join Date: Jul 2003
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well, it seems that its quite normal for the lights to go dimmer to match the other lights(stereo, A/C buttons....) well, i'm paranoid a bit, i just bought the car
![]() ![]() thx guys, John |
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In the shop at Pelican
Join Date: Aug 2002
Location: Los Angeles, CA
Posts: 10,459
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That is correct, when you turn on the headlights, the radio lights should dim.
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Join Date: Jul 2003
Location: NOVA
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John,
It might be an easier task to rule out a battery problem for now. Most of the local parts chains will load test a battery for free. You could still have a bad alternator, but at least you'll know if the battery is contributing to the problem or not. Rich F
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Rich Franco Northern Virginia 1980 911 SC Targa |
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In the shop at Pelican
Join Date: Aug 2002
Location: Los Angeles, CA
Posts: 10,459
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have you checked your battery connections? ive had situations like this where simply cleaning the terminals solved the problem.
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Registered
Join Date: Jul 2003
Posts: 18
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my alternator and battery are in a good condition. it was just another mechanic trying to make money out of nothing. thx for all that replied.
I was checking http://www.logun.org when i found out that the head-light switch is illuminated, i changed the small bulb and its all working fine now. does anybody know if the window buttons illuminate? i mean the buttons next to the transm. ?? thx, John |
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