Hello, I recently purchased a 1994 4runner 4x4 with the 3.0l V6, as my daughter first vehicle.
When the A/C is turned on and running the idle drops from 850 to 500 rpms. If I turn off the A/C the idle comes back up to 850. Is there an idle control valve or idle up switch on these engines?

Thank you

 

Yes. Here's the manual page: http://web.archive.org/web/201102052...23vacuumho.pdf
An electrical signal from the ECM opens the VSV, which puts vacuum to the actuator, which then opens a bigger "vacuum leak" to raise the idle. Test the parts incrementally until you find what isn't doing what it is supposed to do.

 

Thank you, that helped my a ton.. I got it to work and raise the idle speed when the A/C is on!

 

Uh, you're supposed to tell us what you did, so that others can learn from your repair. (Even if it's something you think was "dumb," we learn even more from stuff like that.)

And even though I forgot to say it the first time, Welcome to YotaTech.

 

Sorry, After testing the VSV and looking closer at it I discovered the adjusting screw on the side of it . I unscrewed it a 1/4 turn and noticed the idle increased. I then turned off the A/C and the idle dropped.
I kept adjusting it until I was satisfied with the amount of increased idle with the A/C switched on. As a side note .. I purchased it with 178,000 on it as my daughter first vehicle. It unfortunately was not well taken care of and was not running 2 weeks ago when I brought it home. It has seen its fair share of monkey wrenching by someone in its sorted past.