Question : Charging system drain?

[primesuspect]

My heater fan, when at full speed, slows when i depress the brake pedal. when on the throttle the fan increases speed significantly. Anyone have an idea on the cause? I am thinking alternator, but the brake pedal issue makes me reconsider.

[Azrael]

Some temporary voltage drop seems to be normal for GM cars. Mine always dips on the 3-2 and 2-1 shifts while decellerating. But the voltage should always rebound to ~14.4v at idle unless something is putting a big drain on it.

Use a voltmeter and check the battery and alternator while the engine is running and off.

[robertisaar]

it does sounds like the alt can't keep up with the changes in electrical draw. or your wiring is at fault.

[bszopi]

Pressing on the brakes will cause a load on the engine, which will then cause the alternator to slow down. That is why you see a dimming when you press on the brakes. But yes, it sounds like the alternator is starting to go out.

[primesuspect]

Thanks for the replies guys. I am going to swap in another alternator that I have in "stock". see if that makes a difference. its not new, but it may give me an indication....dont have a voltmeter and im a student so i cant really afford to buy one right now., would almost prefer an obd II scanner.

[RedZMonte]

check your grounds as well. could be a bad/weak ground... i had simmilar issues when my grounding issue was happening.

[primesuspect]

Ground issue, hmmmm. good point. i will clean some of them off tomorrow. I could see that being a contributing factor. the alt may be on its way out as well. If anyone has had issues with the power window switched from the 1996 era olds style switches i just fixed mine. pulled the drivers switch out and pulled it apart. the window lock switch had corrosion on the terminal under the lock button. = water from the window was the culprit. and here i thought my switch was bad.