Please help!

[Bdixon23]

Ok so my 98 mustang has been running like hell when I turn on the air condition. I recently purchased a new 130 amp alternator because I mean I figured it was a bad alternator not being able to run it.. Well I was wrong. The only way I can explain it is when I turn the air on it goes under 500 rpm at idle and then the whole car shakes, almost like its about to die? I don't know it's just very frustrating please help guys

 

[DeepList]

The air conditioner takes mechanical power away from the engine. The blower takes electrical power from the alternator, then the alternator itself takes a bit more mechanical power. I think at highway speeds, the air conditioner takes approximately ten percent of the car's power to run. At idle, it would be significantly more... maybe a third? When the AC is on, the ECM compensates for the additional load by richening the mixture, adjusting idle control flow and injector firing.

A couple of things to check for:

- Alternator issues (which you've already ruled out)
- Worn out or faulty AC pump, maybe a bearing or seal going out?
- Dirty IAC valve?
- Loose belt, maybe ?

That's all that I can think of right now.

 

[chrisv_10]

Yeah maybe a bearing in the AC went out making the pump harder to spin. Like if its about to lock up.

Tapatwerkin

 

[Bdixon23]

Well the belts new to so I for sure check the iac! Thankyou

 

[Bdixon23]

Is it hard to change the ac bearing? Don't really know much about ac

 

[DeepList]

It would probably be better to just change the whole compressor, but I think it's like $150. You'd probably want to make sure that's really what's wrong before you spend the time and money.