Help! Surge/lunge When Ac Is On

[amanda0331]

Ok so i'm going to describe this as best i can...
Whenever I am at a red light or any time my foot is on the brake and the car isn't moving. it will rev up/surge like it's going to lunge forward if i take my foot off the brake. This ONLY happens when the a/c is on. Nothing when it's off.
Any ideas????

 

[Mattstang04]

I have a manual and the engine will sometimes idle up while in neutral, when the a/c fan kicks on. Its a normal occurrence as best I can tell. The engine revs up via the idle air control to counteract the extra load of the a/c fan and compressor running.

 

[wmburns]

The PCM maintains two IAC idle trim values. AC on and AC off.

Here's my take. Your AC is low on Freon. This is making the AC short cycle. The motor isn't idling long enough to allow the PCM to re-learn new AC on idle trim values.

Try jumping the AC low pressure clutch cycling switch to force the AC to run solid for so 5 minutes with the motor hot.

Or fix the AC.

Does this help?

 

[restomod66]

They will always surge just a bit with the AC running, this is common with other vehicle makes as well. However, mine got pretty bad and once I re-charged the AC the problem improved dramatically. I also think you're low on Freon.

 

[amanda0331]

thank you all! I will let you know if these help!