erratic idle when AC is on

[slownlow43]

For a while now I have been having an idle issue while the AC is on. It will fluctuate about 2-400 RPM, but only after I've been driving it for a while. However, the last time it did this it actually killed itself. I've never experienced this with the AC off.

Anyone else have a similar situation, or have a clue as to what is going on? Thanks in advance.

[mastershake]

it could be your idle air control valve

[[ion] C2]

a/c pressure sensor's readings could be bad

i have my wideband O2 sensor hooked up to the a/c pressure sensor 0-5v line, so if i accidentally turn on the a/c (which i don't even have anymore) it will think that the wideband's O2 voltage readings (which fluctuate quite a bit) are the A/C pressure readings, causing the idle to move up and down all crazy to compensate for the A/C load that doesn't exist

[03glgold]

For a while now I have been having an idle issue while the AC is on. It will fluctuate about 2-400 RPM, but only after I've been driving it for a while. However, the last time it did this it actually killed itself. I've never experienced this with the AC off.

Anyone else have a similar situation, or have a clue as to what is going on? Thanks in advance.

does it ever balance out...after i have been driving for a while it will do this for a second and then balance at normal...mine has killed itself once too

[a.graham52]

a/c compresser could be seizing up possibly.

[zzyzzx]

a/c compresser could be seizing up possibly.

I would think that there would be belt noise, or possibly belt damage if that were the case.

How many miles are on the engine?

[slownlow43]

does it ever balance out...after i have been driving for a while it will do this for a second and then balance at normal...mine has killed itself once too

It never balances out. In fact, the longer I let it go the worse it gets. Also, it only does it in park and not in drive.

a/c compresser could be seizing up possibly.

I don't think the compressor is seizing because, like zzyzzx said, there is no noise coming from the compressor and the AC works GREAT.

Update: When I just parked the car at home after work tonight I experienced it again. This time I hadn't been using the AC though. Is there any way to check the idle air control valve?

Edit: Sorry zzyzzx, it just turned 138,000 miles.

[AleroKing]

just had the same problem it was my idle air control, unplug it and if it doesnt affect your idle its safe to say thats your problem.

[Papa Rad17]

you might try cleaning you maf sensor. maybe try sea foaming to. check for exhaust leaks... is running ok otherwise?

[zzyzzx]

just had the same problem it was my idle air control, unplug it and if it doesnt affect your idle its safe to say thats your problem.

Not necessarily so, but IMO idle air control valves are a wearing item and at his mileage it should probably be replaced anyway. I don't trust them past a certain mileage.

[slownlow43]

I'll try changing the IAC out and report back what happens. Thanks everyone.

[slownlow43]

I finally found time to swap out the IAC valve, and it appears to be solving the problem. I'll have a much better idea tomorrow once I get home from work. Thanks again for the help everyone.