Higher Idle with AC on

[rbryan]

My 91 3FE at typical idle is about 600-700rpm, i think this is low, but that's what it is. When I kick on the AC the idle jumps to 800-1000rpm. Anyone have this issue before or can help point me in the right direction? FSM is on its way, but slow in arriving.

 

[CJF]

That's normal. The A/C system kicks up the idle whenever the compressor's engaged. Further, if you're using your A/C and it's not super-hot out, your idle should cycle up and down every few minutes or so as the compressor engages/disengages.

Oh, and idle spec on a 3FE with engine warm, tranny in park, and A/C off is 650rpm.

Curtis

 

[JollyGreen]

I have a 92.
I pulled out my fast idle air bypass and cleaned it and it made it run at a lower RPM when the AC is on.
It is now around 1000 RPM instead of 12-1300.

 

[Lka1988]

When I kick on the AC the idle jumps to 800-1000rpm.

That's exactly what it's supposed to do.

 

[e9999]

yes, it's 650 rpm on the 1FZ too without AC per FSM, and mine goes to 800 or so with the A/C on. All that with a warm engine of course.

 

[BigBear]

My 92 does the same thing as well. 650 without the AC running and 800 with the AC running.