I've got a problem with my wife's '02 Sunfire 2.2L OHV, auto, 80K mi.  Whenever you turn the A/C on, the car surges forward intermittently (especially at parking-lot speeds...safety be damned!).  It isn't your typical power loss type of surge common when you turn on the A/C in most cars, it actually speeds the car up without you touching the throttle.  With the A/C off, the car runs normally.  Hasn't tripped the CEL.  

If anyone has any suggestions, please help.  Thanks.  

Most cars will speed the idle up to compensate for the A/C- but it shouldn't speed up more than maybe 100-200rpms at the very MOST..

You can get the codes read to see if anything's wrong at Autozone or another parts store usually for free.
Otherwise, I'm definitely stumped.

Welcome to the forums, friend.  

I can't help you, though.

Sounds like it's time to visit your local dealership my friend.  They have access to the knowledge and support necessary to diagnose this.  I will check Alldata for you tomorrow at work and see if I can see any TSBs related to this incident.  Sounds very strange to me.

Does the car surge without warning at any time the a/c is on, or only at the exact time it is switched on? Does using the defroster cause the same issue?

QuoteMost cars will speed the idle up to compensate for the A/C- but it shouldn't speed up more than maybe 100-200rpms at the very MOST..

You can get the codes read to see if anything's wrong at Autozone or another parts store usually for free.
Otherwise, I'm definitely stumped.

Ditto on that, whatever controls the idle speed or whatever sends the signal to speed up the idle speed when the AC is on is probably faulty.

I have since talked to a friend who knows just enough about cars to be dangerous tell me to replace the idle-air control valve.  Rather than just throwing random parts at the car until I fix it, I'd like to know for sure that it makes sense to replace that part.  If anyone knows any tell-tale signs of an idle air control valve going bad, please let me know (I thought if those went bad the car ran poorly/strangely all of the time, not just with the A/C on?)

ifcar:
The car surges intermittently any time the A/C is on, but I didn't think to try the defroster on my "test drive" this weekend.  I'll have to ask my wife if she's noticed the defroster causing the surging too since she drives that car most of the time.

Thanks for the help.

QuoteI have since talked to a friend who knows just enough about cars to be dangerous tell me to replace the idle-air control valve.  Rather than just throwing random parts at the car until I fix it, I'd like to know for sure that it makes sense to replace that part.  If anyone knows any tell-tale signs of an idle air control valve going bad, please let me know (I thought if those went bad the car ran poorly/strangely all of the time, not just with the A/C on?)

ifcar:
The car surges intermittently any time the A/C is on, but I didn't think to try the defroster on my "test drive" this weekend.  I'll have to ask my wife if she's noticed the defroster causing the surging too since she drives that car most of the time.

Thanks for the help.

Faulty IAC valves usually manifest themselves with a rough idle/stall.  Surge is possible I suppose, but I would trust you instinct and avoid throwing parts at a problem.  Pay a good tech to diagnose it first--it may seem pricey, but image buying a new IAC valve for say $50 and then not fixing the problem, then throwing another $100 in parts at it and suddenly $70 for an hour of diag time and then the correct part and expert labor and it seems a lot less like taking it in the pooper.

Thanks R-Inge.  I unfortunately agree that it's probably time to take it somewhere.  

Considering how hard it seems to be to work on anything in that car (by comparison my Focus is much easier to DIY repair and maintain), maybe letting someone else cut, scrape, and otherwise burn the crap out of themselves fixing it will be worth the $$ anyway.  

QuoteThanks R-Inge.  I unfortunately agree that it's probably time to take it somewhere.  

Considering how hard it seems to be to work on anything in that car (by comparison my Focus is much easier to DIY repair and maintain), maybe letting someone else cut, scrape, and otherwise burn the crap out of themselves fixing it will be worth the $$ anyway.

Well I am sorry I can't give you more direct help with this, but you make a good point; is doing it yourself really worth the money you save if it takes all your time and energy?  And skin?  

QuoteWell I am sorry I can't give you more direct help with this, but you make a good point; is doing it yourself really worth the money you save if it takes all your time and energy?  And skin?

Sometimes yes, sometimes no.
I've done ALL of the work on my cars since 2002. Nothing extremely major, and I have the Army self-help garages. They have all the tools you need (usually) for free and it's $3-5/hour depending on if you need a lift or just a regular bay.
I usually have more time than money though..

My first job was a cv joint boot, $10 part, the garage wanted $100. Took me 2 hours since I was stupid- the second a few months later took me about 30minutes.
I've done rear brakes, mufflers (actually I cut the old ones off, did all the prep work, and someone charged me $10 to weld the new ones on,) alternator, and all kinds of other smaller jobs.

The kicker was when the clutch went out in the SHO- the local garage wanted $900 to do it, the kit was $300.  I took a week of vacation but didn't get started until Tuesday (Monday I totalled a friend's 1987 3-series that had ONLY 530,000kilometers on it,) and it took me 4 8-hr days to get the work done. Plenty of wanting to throw that car off a cliff..  And again, since I'm mechanically challenged I could do it a second time in less than half that time.

I suppose the real trick is diagnostics- given a few tools any monkey can replace stuff- if I can I know anyone else can...  :D  

Quote

QuoteWell I am sorry I can't give you more direct help with this, but you make a good point; is doing it yourself really worth the money you save if it takes all your time and energy?  And skin?

Sometimes yes, sometimes no.
I've done ALL of the work on my cars since 2002. Nothing extremely major, and I have the Army self-help garages. They have all the tools you need (usually) for free and it's $3-5/hour depending on if you need a lift or just a regular bay.
I usually have more time than money though..

My first job was a cv joint boot, $10 part, the garage wanted $100. Took me 2 hours since I was stupid- the second a few months later took me about 30minutes.
I've done rear brakes, mufflers (actually I cut the old ones off, did all the prep work, and someone charged me $10 to weld the new ones on,) alternator, and all kinds of other smaller jobs.

The kicker was when the clutch went out in the SHO- the local garage wanted $900 to do it, the kit was $300.  I took a week of vacation but didn't get started until Tuesday (Monday I totalled a friend's 1987 3-series that had ONLY 530,000kilometers on it,) and it took me 4 8-hr days to get the work done. Plenty of wanting to throw that car off a cliff..  And again, since I'm mechanically challenged I could do it a second time in less than half that time.

I suppose the real trick is diagnostics- given a few tools any monkey can replace stuff- if I can I know anyone else can...  :D

Yeah, that gig with the Army is very helpful, and of course I can use my lift after hours, but for the common dude it can get quite difficult to drop a tranny in his yard...then again, a friend of mine lowered a friggin turbo350 onto his chest and rolled it off onto the grass one time...then there was the time that the parking brakes didn't hold a car on a ramp and ran him over whilst underneath (broke his collarbone for the second time)...so I like using my lift. :D  

QuoteYeah, that gig with the Army is very helpful, and of course I can use my lift after hours, but for the common dude it can get quite difficult to drop a tranny in his yard...then again, a friend of mine lowered a friggin turbo350 onto his chest and rolled it off onto the grass one time...then there was the time that the parking brakes didn't hold a car on a ramp and ran him over whilst underneath (broke his collarbone for the second time)...so I like using my lift. :D

Jackstands and floor jacks are so cheap, I can't see why people get all dumb.
Even though I use the Army bays whenever I need to do work, I have a couple jackstands, too.  Bought them when I was pulling crap off the SHO to Ebay.
The shifter got me 150 clams! (The original was a cable linkage, from May91 onwards they came with "rod shifters" which are in high demand.)

Quote

QuoteYeah, that gig with the Army is very helpful, and of course I can use my lift after hours, but for the common dude it can get quite difficult to drop a tranny in his yard...then again, a friend of mine lowered a friggin turbo350 onto his chest and rolled it off onto the grass one time...then there was the time that the parking brakes didn't hold a car on a ramp and ran him over whilst underneath (broke his collarbone for the second time)...so I like using my lift. :D

Jackstands and floor jacks are so cheap, I can't see why people get all dumb.
Even though I use the Army bays whenever I need to do work, I have a couple jackstands, too.  Bought them when I was pulling crap off the SHO to Ebay.
The shifter got me 150 clams! (The original was a cable linkage, from May91 onwards they came with "rod shifters" which are in high demand.)

Good deal man!  Parting out cars has its benefits; the whole car my be worth just 500 bucks but the individual parts can yield more than that.   Also I agree; jackstands are a must.  It shocks me how many cars I see being held up by the flimsy little jack out of the trunk...wow

Well, I owned an 01 Sunfire for 4 years and 128k miles - I can definitely say I never came across that.

By the way, why do you say that its so difficult to work on that car? There's quite a bit of room to get your hands around the engine bay.

QuoteWell, I owned an 01 Sunfire for 4 years and 128k miles - I can definitely say I never came across that.

By the way, why do you say that its so difficult to work on that car? There's quite a bit of room to get your hands around the engine bay.

Really?  My 01 Sunfire did it all the time, but I never got it fixed.

Irishguy:

Sorry it took me a while to look at this post again...long story.  

Anyway, it's not exactly that the Sunfire is hard to work on from a space standpoint, it's just that every time I work on it I either get cut, burned, or otherwise maimed by something on it.  Maybe it's just my great luck...but I never seem to have those problems with my '01 Focus and I've done a decent amount of work on it in the 100K plus I've put on it.

Did you ever change the oil on your Sunfire? (Assuming you did, but you know what they say about people who assume...)  I think it's a little bit strange that with all that space in the engine compartment you have to snake the oil filter out from the wheelwell rather than being able to remove it straight from the bottom of the car?  (unless there is some magical secret to removing the filter from this car, I have never been able to fit the old or new filter through the bottom of the car.  I can unscrew the filter from the bottom of the car but the filter won't fit out where my arm went in...)  

I've burned and cut myself more times just changing the oil filter on that car than I have been burned or cut doing just about anything else related to cars, my job, home improvements etc.  I guess that's where I get my love for working on it.  That or I'm just a total idiot and there is some easy way to do it that I am completely missing.  Other things on that car have also cut the crap out of me too though...

QuoteI've got a problem with my wife's '02 Sunfire 2.2L OHV, auto, 80K mi.  Whenever you turn the A/C on, the car surges forward intermittently (especially at parking-lot speeds...safety be damned!).  It isn't your typical power loss type of surge common when you turn on the A/C in most cars, it actually speeds the car up without you touching the throttle.  With the A/C off, the car runs normally.  Hasn't tripped the CEL.  

If anyone has any suggestions, please help.  Thanks.

I don't know if you've found your problem yet, but one thing to check is whether the A/C compressor is cycling on and off...a sign that the freon is low.  This will cause a noticable surge with a four cylinder.