Earlier today I was at a stoplight in the left turn lane, with the A/C and turn signal both on. My idle started going up and down by about 50 RPMs to the beat of the turn signal.

It would only do this when both the A/C and the turn signal were on simultaneously.

After I parked, it hasn't done it since. It has never done it before either.

All engine grounds are secure and tight. The alternator is new, I recently replaced it due to a bad bearing. The belt is not slipping either.

The battery is a remanufactured battery from Advance Auto Parts, about 2 years old.

I'm thinking it's possible that it's the battery but I really don't know. The battery works just fine for everything else.

Any ideas?

 

What was the idle speed at spec with the A/C ON?

Did activation of the turn signal lights reduce or increase the idle speed?

What happened to the idle speed if the headlights were turned on with the A/C running?

 

1. engine was pulsing between around 820-870 RPMs. I know my idle is suppose to be 670 +/- 50, but it's never idled there. I've already tried adjusting that before.

2. idle down with turn signal lit

3. headlights and a/c on makes the idle dip by like 10 RPMs, but no pulsing. Basically, not noticeable.