Surging idle when the compressor kicks on

[briwayjones]

On my '03 Sport I get a surging idle when the AC compressor kicks on in this case because the defrost is on. It surges 300RPM or 400RPM instead of the normal 20 or so when the compressor kicks on. I know this is a fairly common problem but I searched around a couldn't find a solution to the surging idle when the compressor kicks in.

 

[Hartman]

Mine does the same thing, only when the heat or AC is on. Never could figure out why.

 

[briwayjones]

That's not encouraging.

 

[glfredrick]

That is a function of the IAC circut. It could also mean that your compressor is starting to take a LOT of force to turn... Pull the belt and turn it by hand -- see if it turns easy or not.

 

[briwayjones]

Hmm, so it could possibly be bad bearings or something in the compressor. I would think it would make noise if that was the case though.

 

[budwich]

as pointed out, the IAC is one area.... its relatively cheap and easy to replace.... and if it hasn't been replaced yet, its probably near its end of a "good service life". The other area is probably more likely and that's just overall engine load at idle is probably outside the "normal range" of the control system in terms of "smooth operation". By that, I see that you have a "few extras" on your vehicle... nothing wrong but it is maybe likely that you are running engine idle load at the "high end". Then when your AC cycles, this adds both an electrical and mechanical load on the idle system. The system tries to adjust and does cause you don't get a stall which is good. However, it isn't as smooths as you "expect". Measure you amperage output on your alternator. It might give you an idea of "system load".

As suggested, your ac might be having a problem.... when was it serviced??? might be low on oil causing the compressor to work harder than usual.

 

[Hartman]

In my case, it very well may be the IAC....I've cleaned it numerous times to squeeze more life out of it. It just doesn't seem like the compressor is working harder, or else the surges would be less uniform, or at least that's how I see it.

 

[briwayjones]

as pointed out, the IAC is one area.... its relatively cheap and easy to replace.... and if it hasn't been replaced yet, its probably near its end of a "good service life". The other area is probably more likely and that's just overall engine load at idle is probably outside the "normal range" of the control system in terms of "smooth operation". By that, I see that you have a "few extras" on your vehicle...
As suggested, your ac might be having a problem.... when was it serviced??? might be low on oil causing the compressor to work harder than usual.

Well I don't really think it's the IAC although I haven't checked it. It only has 44,000 miles on it. I also don't think the engine is under anymore load than normal, I don't have any accessories installed. It's surging way beyond what would be normal under even a hard load on the engine. And it's more often than usual about every 5 seconds as opposed to every 20 or so.

 

[zims666]

any results?
im having the same problem...

 

[IZwack]

Mine has been doing this for years, I thought it was normal

 

[briwayjones]

any results?
im having the same problem...

I actually haven't had a chance to mess with it yet. I've been keeping the heat off of the settings that use the compressor if I can avoid it.

 

[zims666]

I actually haven't had a chance to mess with it yet. I've been keeping the heat off of the settings that use the compressor if I can avoid it.

i took my IAC off and cleaned it. problem solved.