A/C or Voltage Problem?

[mikevyota]

I drive a 97' Mustang, 125k miles and recently the A/C starts cycling, the rpm's drop, the voltage gauge drops and the car bucks a little at the top of first gear.The idle always come back up right away, but sometimes it does this two or three times before settling down. Car is T-5 5-speed. Seems to do this only at extended idle and leaving a light. At cruise or on the highway, it doesn't miss.

The alternator is new, replaced yesterday. I checked it running, before it was only 13.2 volts, now it's 14.59 volts with all acc. on. The car only misses with the A/C on. The compressor, condenser, dryer are all on their second summer( Las Vegas heat, It was 116degrees yesterday!!!!), and only started doing this two days ago. Is there an idle "bump" switch for when the A/C is on? Or something else that I'm missing?

All help is appreciated!

 

[raz54]

The IAC is what speeds up your idle when the AC is switched on. It may be sticking and still not trow a code. You can try to clean it with brake or carb cleaner.

 

[mikevyota]

I put a full charge on the battery, and the idle problem went away. Guess the A/C doesn't like to run without full voltage.

 

[Mustang5L5]

You already had a full charge. Anything over 12v is charged. At 13.2 you still should have been fine.


Did you disconnect the battery to charge it? If so, you reset the compute and that most likely did the trick. The problem may come back, so keep an eye out.

 

[mikevyota]

Wow, that took a while for a reply. No, I didn't remove the battery, just drove the car til the new alt charged it back up. Have since sold the car way too much $$$.