Idle surge with A/C

[isjoining]

Just like the title says, I'm getting idle surge when the A/C is on (at Max A/C, Normal A/C and front defrost). the idle surge is at its worst when its set to max a/c or defrost and the car goes up and down 400-500 rpms and sometimes it almost stalls. obviously this happens when the car is stopped at a light or stop sign. No CEL, any ideas?

 

[FordTard]

BUMP...

I am having the exact same problem... So I am very interested in this answer and will fallow this thread.

I think it may be the IAC but not really sure how to check if it is.

 

[isjoining]

yeah i was thinking IAC as well, but wouldn't it happen when its set to vent or off and not just A/C? my car idles perfectly fine with the vent setting.

I'll have to check my IAC tomorrow morning.

 

[FordTard]

This is just my brain storming not sure if i am even on the right track...

I think when the ac is on the compressor puts more load on the engine so the rpms fall a little and the IAC keeps them constant. but our IACs may be shot, there for it surges. And it does not do it on vent because the compressor is not on and not giving the added load to the engine at idle.


Thats my hypothesis.

But would still like more input and maybe a way to check if it is the IAC before i order a new one.

 

[isjoining]

i just checked my IAC, doesn't look dirty at all so it can't be that. found another thread regarding the same issue here: http://forums.stangnet.com/744687-stang-hesitates-buckles-c.html

oh and apparently there is no idle surge with the A/C on when the car is in park, only when the car is in gear

 

[squeak93]

Is your clutch on the ac going bad? IF its draging the rpm's down the iac may be tring to compensate, therefore giving u the surge.

 

[isjoining]

is this what you're talking about?

 

[squeak93]

I can't see pics at work.... Sorry.

 

[evil281]

i cant see the pics either at work but it should be a round couple mm's thick plate with 3 round smaller circles that has bolts going thru it, check to see if its loose or rattling and leave the ac on and listen to it will the hood is open

 

[isjoining]

ok thats what the pic is showing, as far as i can tell, i don't hear any strange noises or see that its loose with the A/C on and air all the way up.

 

[evil281]

mine rattled when is was worn, id assume it woould be similar on urs if it was worn too, must be something else then

 

[Kraw]

I'm having the same issue. 2001 with 100k miles

I'm assuming it's the clutch too, so is that difficult to change?