I hope this is the correct thread. I have been driving this same IROC every day to work for the last 10 years or so. Recently I had to have the A/C replaced on the car because the old one died (I used an AC Delco part). After I did this, when the A/C was running, the voltage on the car would drop way down at idle. So much so that the car would miss on acceleration from stop. The shop told me the alternator was not putting out enough juice, so I replaced it. I have the same issue.

Any ideas on this? I thought perhaps the alternator was junk, but like I said, i just replaced it, and the voltage is well over 13 without the AC.

 

Are you using the right alternator,you should have a 108Amp alternator.

 

Any alternator that is considered bad should be tested before being replaced if possible. AutoZone does it for free and usually only takes a few minutes after you wait in line.

I'll assume you mean voltage not amps. If it only does it when the AC is on, then it could be an issue with the pressure switch going bad. If the switch is bad it won't kick off the compressor and keep on running it until the car wants to die.

I'd personally find a new shop. They should have had the alternator tested before they replaced it. Some parts stores can even bench test stuff with it outside of the car.

 

The shop did test the alternator and they said it was not putting out enough power. And I do mean volts, sorry. So the old alternator was putting out over 13 volts without the AC, and this new one does the same. The voltmeter with this new alternator actually appears to be reading a higher voltage than the old alternator, but it still drops down to 9 or 10 volts with that AC is on.

I have been buying these lifetime alternators at Oreiley's for the last 15 years or so. They suck and only seem to last about 4 years before I need a new one, but I do not recall ever having the voltage drop down at idle when the AC is running.

Now the car will not die when I come to a stop, only hesitate at acceleration for a split second. Forgive my stupidity, I am not real talented with the workings of the car. Where is this pressure switch?

 

Had about the same problem. Engine miss and low output from alt. IT would test good ---------if you shut everything off. Traced problem to stero system. It`s one of those high out put things-------------with a HIGH INTAKE to work if you know what I mean! My cure was a 220 amp alt I got on E-Bay with a fiuse kit for both Pos. and Neg. sides going from alt. to battery. Now stay arond 14 volt on meter but no more miss turn signals work head lights don`t go dim at stop lights--ETC.
Good luck.