Is it my alternator or battery if it does this?

[Vito117]

I've noticed that when I start my car in the morning to warm it up I'll have the lights turned on and defrost/fan set on high......I notice the lights are a bit dim and that the defrost fan isnt really blowin full blast.....then when I take off...a couple of blocks down the street....the car seems to come to life...the lights are brighter....fan starts blowing higher.
Is this normal?...alternator?....battery?

 

[Vito117]

by the way...
1993 ATX
146K

 

[SHOZ123]

Sounds like a low rpm/alternator problem and you are discharging the battery while the car is warming up.

 

[Rob94]

It could be the alternator. Then again, you've got the lights on, blower fan on high, I would assume the radio playing. Probably the rear defroster as well. You are putting quite a load on the electrical system. My opinion is that this is normal. Most cars I've owned or even ridden in do this very same thing. The simple fact that once you start driving, the lights brighten and the blower fan increases speed tells me the charging system is doing just fine. Opinions vary of course, and others will insist that there is a problem somewhere. To each his own, and good luck to you.

 

[rendyx]

I noticed my blower fan becamne weak when I had alternator issues. It may be getting weak, but you are putting on a heavy load. Go to Autozone and have the alternator checked for free. I would think it can be a little below what it should be if it is old, however, if it's putting out 24 amps like mine was, it may be time for a new one.

 

[NotSoSlowSHO]

Listen to Pat...

It does sound like your alternator is on its way out... getting it checked will show for sure.

Feel lucky that it didnt just die on you with no warning thumbs_u

 

[BlackMagik]

Take the guss work out of it and test the system.

With the engine off you should read 12+ volts DC at the battery terminals. Anything lower and it's an indication that the battery is on it's last leg.

With the engine on, after a 10 minute warm-up, headlights on, heater on, you should read about 14.7 volts and not under 14. 14.8 is optimal for most replacement alternators but the numbers vary slightly with brand. If you don't get something close to this check for corrosion at the terminals and tighness of connections before you swap alternators.

If you don't have a multimeter you can usually buy one a basic one for $20 or you can just go to the auto parts place and let them "load test your charging system".

Hope this helps.

 

[sdpatt]

At least in the AUTO position, the ECC will use a low fan speed until the coolant temperature has reached a minimum value to prevent blowing cold air. I don't believe that the FLOOR ro VENT positions do this.

The lights on the other hand, should not change intensity.

 

[Trojan Man]

Every car I've owned has done the exact same thing, including my SHO with a BRAND NEW alternator in it. Most alternators put out peak power at around 2000 rpms. When you're car is idling you're at only about 900 rpms. With all the accessories on you are drawing a fair amount of power (especially that rear defroster). When you start driving, the car goes up to 2000 rpms and you are thereby feeding your whole system a higher voltage, hence the increased intensity of your lights.