Battery Voltage Help

[New 5.0]

I have a 95Gt and this past weekend the battery voltage started to act up. When i would turn my a/c on the needle would get real close to 8 volt and felt like it wanted to shut off. When i turn the a/c off it go's back up to around 14-15 volts. I took it to advance auto parts so they can test the alternator and battery. My battery was good and alternator was bad. So i replaced it, the problem is still there just not as bad. :help2:


ANY IDEAS???
Need help fast!!

 

[95-stang]

Nothing wrong with your air con pump is there, sounds like it might be putting a lot of load on the belt?
As you may know, the pulley freewheels until the a\c is switched on, then the "clutch" engages and works the pump.

 

[New 5.0]

Nothing wrong with your air con pump is there, sounds like it might be putting a lot of load on the belt?
As you may know, the pulley freewheels until the a\c is switched on, then the "clutch" engages and works the pump.

I Been hearing a Squeaking sound coming from that area but i figured it was the alternator. If it is the air pump would i be able to fix this on my own?

 

[95-stang]

Squeaking is often the tensioner is weak, so the belt slips, maybe turning on the a\c is just making it worse.
Might be worth looking at the belt tensioner first.

 

[New 5.0]

How would i know if the tensioner is bad? From what i can see it looks fine. The squeaking only happens when car is cold.

 

[95-stang]

Did they not test the voltage after the new alternator was fitted?
I would pop it back and ask them to test it with and without the a\c on, that would help narrow it down, the stock voltmeter is'nt dead accurate.

 

[New 5.0]

No i havent had it read. I did the work myself

 

[New 5.0]

What else can cause this problem???

 

[New 5.0]

How would i know if the tensioner is bad?

 

[New 5.0]

Hey Guys!

Still no luck with this voltage problem. Now when i turn my lights the meter drops and when i have the a/c and the lights its worst. :help2:

Any ideas?????

Please need help..

 

[95-stang]

Ok,, borrow, buy or steal a Voltmeter, with the engine running and nothing else switched on, whats the reading across the battery terminals?
No point in going any further till thats done.

 

[New 5.0]

How much do they go for?

 

[95-stang]

My digital voltmeter cost me about just under £10 or about $20 .

 

[Downshift]

Dude you can even go to auto zone and they will let you borrow one or they can use the charging system tester on it and it will tell you amps and voltage and its free.

 

[Goons GT]

while your at autozone have them do a load test on the battery, car off and the meter will put a load on the battery. It sounds like the tensioner doesn't have anything to do with it if your gauge is dropping when you turn your lights on, those two aren't connected. There are two ways to check it though, 1) there should be an arrow on the front of the tensioner and two marks for the range, the arrow should be in the middle or so, with the car off, if the belt is good. 2) with all the accessories on take a look at the tensioner and see if it is bouncing real bad and if the arrow is still in between the range marks.