RPM jumps around when A/C is on

[neikoblu]

I got my A/C charged and when I turned it on, I noticed that at an idle my car almost died and one time it did. The idle jumps from like 1100 to 450 or so, UP and DOWN. When I turn the A/C off, the engine starts to level out. It just pisses me off. This idle bull**** is the only thing that I can't figure out and the only thing that pisses me off about my car. Any ideas!

 

[5.0 con-vert]

That seems pretty bad. I know that once that compressor kicks into gear it usually drops the RPM's a little bit but not like what you are experiencing. Is that compressor in rough shape and just giving too much resistance for the motor to handle? Maybe the bearings in that are about shot

 

[5spd GT]

Mine does the same thing...but not quite the rpm jump your experiencing. I think it is happening when the alternator is getting overrun possibly on mine because when my a/c is running my e-fan kicks on as well...???

The a/c drag might be lowering the rpm of your engine and then it trys to compensate it (to keep from dieing) and "overrevs" it...

What is your idle set at normally?

 

[neikoblu]

My idle is set at about 800-900 but when the a/c is on it drops pretty low. I have a 3g alternator so the charging is not a problem. Really the car wont idle very well with the a/c off I give it some gas after I start it and it idles out okay. But after the initial start it jumps around for a minute before the idle settles down. I have set the TPS to .98 and I put one of those IAC spacers in hoping that would fix it. Would the EGR play a role in the idle problem?

 

[jrichker]

Se the Sticky " Help me create the Surging Idle Checklist" at the top of the forum for help.

 

[jaackal]

this happen to me before and the high pressure switch was shot, it also happened to my brother and it was his oxygen sensors