Air conditioner effect on current draw

[jhm]

Hi GMTECH,

I noticed the last few days when I have the air on and the fan blowing, when I apply the brakes, the fan speed drops. Do you have any thoughts on this? I had the alternator replced about 2 years ago because it was overcharging, it was still in warranty and they replaced it with a Delphi rebuilt unit. I am wondering if this one is going bad as well. Volt meter shows 14 volts when air is on, usually it is around 14.5-15 without air. Thanks.

[bobcat5544]

WHATS THE YEAR, MAKE, MODEL, AND ENGINE

[jhm]

WHATS THE YEAR, MAKE, MODEL, AND ENGINE

 

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2001 silverado 4.8L 4X4 EXT CAB

[bobcat5544]

DOES YOUR TRUCK HAVE AUTO TEMP CONTROL, WHERE YOU ARE ABLE TO PROGRAM WHAT TEMP YOU WANT YOU AC TO STAY AT

[jhm]

DOES YOUR TRUCK HAVE AUTO TEMP CONTROL, WHERE YOU ARE ABLE TO PROGRAM WHAT TEMP YOU WANT YOU AC TO STAY AT

 

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No.

[GM-Tech]

What level of change in the blower are we talking about? Barely perceptible or obviously noticeable to anyone in the vehicle? Brake lights aren't a big load, so I wouldn't expect a noticeable change, if any, under normal conditions.

 

If the battery is in good condition and at a full state of charge, it should be able to compensate for any brief needs over and above the norm. Typically, the alternator takes care of the electrical needs but during times of heavy loads, the battery helps.

 

If the alternator output (and lets talk about amperage output, not just voltage) is low, the battery will also slowly degrade in its level of charge and be unable to help under these conditions.

 

So without some checking, you can't say this problem is the alternator or the battery. One can affect the other.

[jhm]

What level of change in the blower are we talking about?  Barely perceptible or obviously noticeable to anyone in the vehicle?  Brake lights aren't a big load, so I wouldn't expect a noticeable change, if any, under normal conditions.

 

If the battery is in good condition and at a full state of charge, it should be able to compensate for any brief needs over and above the norm.  Typically, the alternator takes care of the electrical needs but during times of heavy loads, the battery helps.

 

If the alternator output (and lets talk about amperage output, not just voltage) is low, the battery will also slowly degrade in its level of charge and be unable to help under these conditions.

 

So without some checking, you can't say this problem is the alternator or the battery.  One can affect the other.

 

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It is noticeable to me because I am prone to picking up on things like this. My wife, I am sure, would not notice it. I still need to take it in for the mystery Dexcool drips. They replaced the battery when the side post rotted off, and like I said, the alternator when it was overcharging. I will ask them to check the charging system as well. Thanks for the reply!