Power drop

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Dec 8, 2003 | 07:13 PM

David26

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Junior User

Joined: Feb 2003

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From: Woodstock, Ontario

Power drop

I just started noticing this on my Aerostar now that the cold nights are here. When I start up my van in the mornings everything works as it should, but when I turn on my windshield defrost and rear defrost, all the interior lights dim and the RPM's drop slightly. This is the first winter this has ever happened and the van is 15 years old. And when I'm driving with the defrost on and I use the turn signal, the signal flashes really slow, but when I turn the defrost off, the signal returns to it's normal speed. I don't have any extra electrical components hooked up to cause this drain. Could it be that my alternator is starting to die? Any thoughts would be appreciated as it's only going to get colder. Thanks.

David

Dec 9, 2003 | 12:29 AM

xlt4wd90

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Joined: Sep 2003

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From: SoCal

What is your engine's idle speed when the dimming occurs? Do the lights still dim if you rev the engine a little? If the lights return to normal brightness, then the alternator may be OK, but your engine is idling too low. You should check to make sure that your engine's idle is set properly. If it's a carbureted car, you should set the choke and cold idle screw.

Dec 9, 2003 | 07:45 AM

tom_foreman

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Joined: Dec 2002

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From: Georgia

xlt4wd90 is correct.

Remember that the rear window defroster is a big electrical element that uses electricity to heat the glass. It's a big electrical drain. Second, when you run the front defroster, the A/C runs too putting a load on the engine slowing it down too. Most vehicles have a throttle kicker switch or something to increase the idle of the engine when the A/C is running. You may have a problem with this.

If you are concerned about the alternator, take it to Autozone or your local parts store. They can check out the battery and alternator in the vehicle.

Dec 9, 2003 | 11:23 AM

aerocolorado

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Joined: Apr 2001

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For what its worth - I noticed the same thing last night during our first snow/ice storm of the season. Using the rear defrost element puts a big drain on the electrical system. I agree with the previous posters regarding the low idle speed. Since you tend to drive slower on ice or when your vision is limited, your engine speed is also less and you notice the drain more. Your slow turn signal may be an early indicator your battery has seen better days and is holding less than optimal amperage.

Dec 9, 2003 | 11:37 AM

rlmdad

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Joined: Aug 2003

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From: Corpus Christi, Tx. 78418

Just my 2..but I agree with aerocolorado, have your battery checked, it has probably seen its better days. LOL

Ron

Dec 9, 2003 | 11:43 AM

David26

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Junior User

Joined: Feb 2003

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From: Woodstock, Ontario

The battery is bought brand new last year with a 1000 cold cranking amps. The speed at which I'm travelling doesn't seem to matter either...be it 60km/h or 80km/h.

Dec 9, 2003 | 03:58 PM

rlmdad

Senior User

Joined: Aug 2003

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From: Corpus Christi, Tx. 78418

If you're sure the battery is ok and does not have a shorted cell, then I might suspect that your alternator/voltage regulator may not be able to handle the additional load of the rear defroster. It may not be providing enough power to recharge the battery, run the blower motor(s), power the rear defroster and turn signals all at the same time. You could check the diode pack to see if any are blown. I've had alternators with as many as two diodes out that still indicated ample voltage output, but that had low amperage. Just a thought.

Ron