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A/C and Idle Issue

Discussion in 'SN95 Cobras' started by 97RioRed4V, Oct 6, 2013.

  1. 97RioRed4V

    97RioRed4V Member Established Member

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    Location:
    Peoria, IL
    I had the A/C recharged and it worked great for three months. The other day it started blowing warm air and idling erratic. It kept cycling between 600 and 900 rpms. Would a bad a/c compressor cause this?
     
  2. MustangMatt77

    MustangMatt77 Member Established Member

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    Location:
    Union City, OK
    I'm not sure a bad compressor would cause the idle issue, you may have a bad IAC. do you have idle issues without the A/C on?
    I know when I turn mine on it causes an adjustment in the idle. I would get a can of a/c leak finder. Your compressor may be fine and you got a leak in your high or low pressure line. I would not us your a/c till you recharge to check for leaks, if your compressor is fine but all your PAG oil leaked out, you will fry your compressor.
     
  3. CobraHuck

    CobraHuck Member Established Member

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    Location:
    Dacula, Ga
    My car has an erratic idle with the a/c on, very similar to yours. My freon got really low here recently and the compressor was kicking on/off wayyy to often. My dad was saying (he was a mechanic for a long time) that the fittings on these 134 systems are different from the older systems and as they age, they just naturally slowly leak.

    Just recharged it and it does bog the idle down with the a/c on but it stays consistent now.

    I haven't looked too much into it yet, but I'm thinking my IAC may be on it's way out. Another thing to check out be your compressor cycle switch to see if it's bad.
     
  4. MustangMatt77

    MustangMatt77 Member Established Member

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    An easy check for your IAC is to start the car (no throttle, idle only) and then tap on your IAC with a screwdriver handle or similar. If your idle changes, most likely it's going. There is no real way to clean it out. Yes you can spray it with carb cleaner and yes you can let it sit in there but it won't clean it all out. New IAC's run about $40 wether it's at a local auto store or online say at rock auto. Difference is do you want to pay shipping? Yes you can get a motocraft valve on line or an AC Delco or similar at a local store. Your call.
     
  5. Sn8kebitten

    Sn8kebitten Active Member Established Member

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    So just replacing the IAC will clear up all idle problems when the a/c is on? Mine has never had idle problems without a/c but every since I bought the car in 2009, sometimes with a/c on, it'll idle super high when I throw it in neutral while coming to a stop. Like 1800-2100rpms. And then it will drop down after I've came to a stop and almost die. Also when just cruising down the road, you can feel it kick every now and then almost like I let off the gas real fast.
     
    Last edited: Oct 7, 2013
  6. 97RioRed4V

    97RioRed4V Member Established Member

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    Sep 17, 2012
    Location:
    Peoria, IL
    My car does a little rough if you compare it to a brand new car. I can check the iac tonight. What I find strange is I had cold air blowing then this happened instantly. I think I need to investigate the a/c switch mentioned above. I will have to investigate how to do that..... Thanks guys!
     
  7. MustangMatt77

    MustangMatt77 Member Established Member

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    Location:
    Union City, OK
    It won't clear up all idle issues, but I believe it does play into the problem. Mine has been running fine, it will idle different when the AC is on, but now (last 2 days) it is doing it without the AC on at start up, it will almost die if I don't give it gas, but after warm up it runs fine. I'm going to check my egr as well.
     
  8. 97RioRed4V

    97RioRed4V Member Established Member

    Messages:
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    Sep 17, 2012
    Location:
    Peoria, IL
    I turned the car on tonight. Idled good until I turn on the A/C, MIX, or Defrost. I tapped the IAC, but no change. I checked the voltage to the IAC and it was 12V. I think the IAC is okay. I need to understand the A/C Charge Clutch Switch. Can I check the voltage to it ? Can I then bypass it and see if the A/C turns on? Unfortunately to change this switch I would have to get the A/C discharged! Any thoughts?
     
  9. STAMPEDE3

    STAMPEDE3 SAULS BROTHER Staff Member Super Moderator

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    It is supposed to idle up when the compressor kicks on.

    So if you are having A/C issues and the compressor is short cycling like the other guys was then yes, it will swing the idle all over the place.
     

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