Rough Idle with A/C on

2004 Prerunner 3.4L
When I have the A/C on the truck idles up and down between 500-800 constantly. It just doesn't go up and down when the a/c engages and turns off, As soon as i turn off the a/c switch it idles perfect. any suggestions. i will post a video tomorrow if needed.

 

Wow , weird m 2001 4 cyl is doing something similar but almost the opposite. Mine idles rough (high, with some jump) when the A/c is OFF , but when i turn the fan on high with A/c the idle comes back down to normal. Very strange. I have the CEL on too reading out idle valve malfunction , anyone got any ides with this A/c connection?

 

I don't have any codes. Just idles up and down

 

Normal my man, the motor gets loaded up when the Ac comes on, thus the RPM drop, PC sees this and kicks it back up again.

 

Not saying this is what's happening to you, but I remember my buddy buying an older Honda Civic for his mom, and it did that. It was our first indicator of a leaky/blown head gasket.

 

You need to address your MIL first about the IAC and then see if you have issues with your AC(I doubt you will).

 

sorry its been a while. Does anyone know the easiest way to post a video from my phone?

 

is a/c blowing cold air? Idle up and down is typical when a/c is on.

 

yes it blows cold. It hasn't always done it. Its not a low idle for a second and then back up, its a constant up and down pretty quick. i have a video from my phone but i cant get it to post