AC/Alternator/Fan question

Discussion in 'OT Driven' started by 4W4K3, Mar 13, 2007.

  1. 4W4K3

    4W4K3 New Member

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    1993 Nissan Altima GXE

    Air conditioning works great. Has worked since I bought the car 22,000 miles ago. Alternator has never failed either, and the fans are the same story.

    However, when I run the A/C I have a weird idle/RPM problem.

    When I turn ON the A/C, everything works great. Blows ice cold, no issues.

    Then it runs through a "cycle" with the fans spinning up, then shitting down periodically. Normal.

    When the fans SHUT OFF, my idle plummets. My engine will physically shake back and forth for a few seconds until it resumes normal idle. MY RPM's drop to 200-300, should be closer to 750-800 at idle.

    Asked a friend, he said it's my alternator. He said the fans are taking ALL the amperage while they are on, then when they shut off ALL that load goes on the alternator (102amps?) and it "overlaods" my system for a few seconds.

    What do you think? Is that bull, or am I looking at getting new fans? Or worse yet, and alternator? :sadwavey:
     
  2. MaximaDrvr

    MaximaDrvr Member

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    You could have a bad diode in the alternator, but that wouldn't make sense to describe the problem that you are having.

    There is a problem with your system though, but it doesn't sound like, from your description, that it is electrical.
     
  3. 4W4K3

    4W4K3 New Member

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    Someoen else told me to clean/replace my IAC unit. I have yet to find the time to take it out and clean it...but hopefully that helps my idle when the fans shut off.
     
  4. alltracman78

    alltracman78 New Member

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    It sounds like the ECU is taking a second to adjust to the new inputs. It could be alot of things.
    It won't hurt to do a fuel injection service [a good one]. The IAC valve could be sticking a slight bit too. It certainly won't hurt to clean it out.
    What's the condition of the plugs/wires [does it have a dist or is it distributorless?] cap/rotor?

    If your car is demanding full amperage from the alt, the alt will ALWAYS be under that load, as long as the amperage is being used. The load doesn't transfer to the alt, it's already there.
     
  5. 4W4K3

    4W4K3 New Member

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    New plugs and wires about 15K ago, they are still looking good. I had the distributor and PVC valve changed maybe 7,000 miles ago, they should be working 100%. Cap and rotor are also about 15K old. Honestly I try to keep up with my car, when it hit 100,000 I ordered alot of OEM engine parts and just started swapping things out. But I didn't do any kind of A/C work or intake mods or anything.

    I ran SeaFoam in my car about 3,000 miles ago, right before my last oil change. It smoked and all and my car's idle improved, seems to rev stronger, etc. But it didn't slve the current problem.

    Still have to take out the IAC and clean it. I think Wednesday I will have the time, will be my first day off in a week lol. I work in a car garage and the "fuel system service" we run is EXACTLY like SeaFoam...we just charge about $120 for 3 bottles lmao.

    BTW 2 of my fuel injectors are new as well. The other ones read withing spec (10-15ohms resistance) and haven't given me problems. I replaced the other 2 at the same time as the plugs and distributor.
     

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