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Full Version: Car almost stalls when ac/defroster is turned on
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i have a 98 plymouth breeze 2.0 4 cyl...idles smooth at almost 1000rpms until i turn on ac or defrost then the car almost wants to die everytime the ac compressor kicks in and if stopped in gear with foot on brake it has stalled a couple times.....when its not on it idles and runs perfect...someone mentioned the iac valve? could that be my problem?
Yup, that could very well be the problem.

What I would do before replacing it is get a can of throttle body cleaner and soak everything down. When the throttle area looks good find the side port for the IAC in front of the butterfly and soak that as well. You will need to remove the rubber boot between the air filter and the throttle body to do this. Reassemble and start the engine. If the first try doesn't do the trick then soak the IAC port one more time and see what happens.

Best case you have spent under $10 and the problem is solved. Worst case is you cleaned stuff that needed cleaning ayway, which means you don't have to do it again and you can just replace the IAC. This part should be available in the aftermarket for substantially less than the dealer.

Let us know how you make out as other may learn from your experience.
ok Im back...i took apart the IAC from the carb body and it was black as heck with carbon...I cleaned the whole thing with carb and throttle cleaner and made it look like new and also did the carb..put everything back together and its still doing the same thing....could the IAC be bad and if so how do you know ? is there a way to test it? i do have a multimeter if needed...but also this part goes for about $80.but have found it on ebay new for $11.00 so should I just buy it and replace or like I asked is there a way to test or could something else be my problem? any help well appreciated..
Yes that IAC could be bad and you could buy the one on eBay for $11 but my experience with the cheap ones is that they also go bad in short order. My local part store stopped selling them because they had a 50% failure rate and the customers were hetting rather upset.

There's no easy test with a meter because what usually happens is the moving parts wear out. IOW, all the meter will tell you is if the motor is good. If you apply voltage to it you could watch it work in one direction then reverse the wires and watch it fly apart. You really can't prove much besides your ability to find small pieces across the garage. (just joking)

Now, before you blow $80 I'd carefully inspect all of the vac lines because that can also cause similar problems, although that usually will set the check engine light on. A sticky IAC usually doesn't

BTW, I got away with cleaning the one on my Grand Caravan several times but it came down to doing it once a month then it finally crapped out. I was going to find the cheap one and sell the car. Good thing I didn't because 2 years later I still have the car and everything is still cooperating.
Well i ordered a new IAC valve...i will report back once i recieve it and install.crossing my fingers!..also if this isnt the problem i was told my next step would be to look at the round defroster switch not the one that has the a/c on it but the right one with the defrost on it....that if the switch is bad that this would also cause this problem too...could this be the case? there a way to test this with a multimeter?..
I think someone is pulling your leg. The electric defogger (rear window and sometimes the lower portion of the windshield) doesn't draw enough power by itself to be noticed. Most larger electric draw items could change the engine speed by about 50 RPM each, so headlights, wipers, defogger, blower, should total no more than maybe 100 - 200 RPM but only if the IAC was not working. Cranking the steering wheel (ps pump load) and turning on the AC might be another 100 RPM each, which is probably what's stalling you out when the IAC doesn't respond.

Keep us posted after you get the new part installed.

BTW, do not attempt to power up the new IAC before installing it as it could be damaged. If you are really curious then plug in the old one while laying on a shop rag and have a helper work the key so you can watch.
ok well i received the new IAC and noticed right away the "bullet" end of the part was 1\4" shorter from the end of the bullet tip to the first shoulder...i measured 3/4" on the new one and my old one is 1" so it didnt idle when the car started went to 3-1/2 thous the website I bought this from said it was for this car. why would it be shorter in length? The other pics i looked at from other sites all look shorter too not that you can tell much from just a pic especially if its just a generic pic and not the original
Ahhhh, the joys of buying stuff on the web!

Perhaps it's time to take a trip to the local parts store and compare? They may have a foot note saying that only fits with xyz option. IOW, there's more than one part number or something is different between early and late production in the same year.... turbo or non turbo, etc.

Another thing to consider is if the car ever had any major work before you owned it. Perhaps an engine change from a different year?
So i get to work and tell my story to my coworker that was a former mechanic and he says the length shouldnt matter that they do come a little shorter...he told me to disconnect the battery for about 5 min then try starting it...he said the computer will sync with the new iac that way and should find the correct idle...does this sound feasable or just a waste of time?..
I don't think it wil hurt anything and it might satisfy some curiousity. As for wasting time, that depends on how much you have and how long it wil take to put it back in.
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