My car has been acting up for a while now with the following symptoms:

When idling and with the A/C running it will run fine for a few seconds but then the car will sort of shake and the A/C will start blowing warm air and the whole car will act like it wants to turn off (and sometimes will).

I've replaced the spark plugs and spark plug wires (and was extra careful to make sure the spark plugs were gapped properly). So now I'm thinking it could be the fuel injectors.

My question is this: is fuel injector cleaner that you pour into the gas tank worth the money or should I go ahead and take the car to a mechanic? Also, with simple tools at home (no lift, no diagnostic machinery, and only a basic tool kit) is it possible for someone to change the fuel injectors themselves without causing a lot of trouble, or should it be left up to the professionals?

  • 1
    This doesn't necessarily sound like a fuel injector problem - it could be a problem with your AC compressor. Have you looked at it yet?
    – Rory Alsop
    Aug 20, 2012 at 8:46
  • Not yet. Honestly I just assumed it was a fuel problem because of the smell.
    – user2121
    Aug 20, 2012 at 16:04

2 Answers 2


This doesn't sound like fuel injectors at all. My first to suspects are the IAC (Idle Air Control) and the AC compressor.

Does the AC work fine otherwise? When not at idle. If so I am leaning more toward the IAC.

The computer on the car maintains idle speed by opening and closing a small air passage with a stepper motor. When you turn on the AC and put the car under more of a load the IAC should open up to compensate for the additional load. The passage may be clogged, or the motor may be bad.

I would remove the IAC and clean the passages, and the throttle plates with carburetor cleaner.

  • Yes the A/C works perfectly otherwise. Would this account for the fuel smell as well?
    – user2121
    Aug 20, 2012 at 16:03
  • @AaronLang Yes, the fuel smell would be from the wrong fuel mixture, running too rich for example. That is if you notice the fuel smell at idle mostly Aug 20, 2012 at 16:04
  • Yes that's exactly when I notice it. After the strange hissing sound and as te air becomes warm. I'll do this today and see how it works out.
    – user2121
    Aug 20, 2012 at 16:12
  • @AaronLang You should also check for a vacuum leak. Also it would be a good idea to include as many details as possible when you ask a question even if you don't think it's significant Aug 20, 2012 at 16:18
  • What's the best way to check for a vacuum leak?
    – user2121
    Aug 20, 2012 at 18:30

We just had this fixed on a 2006 Cruiser. It was the cooling fan not running when needed on low speed. When stopped there was no airflow through the condenser, a/c pressure goes up, loading down the engine (slowing it and making it rough). In our case it was the fan, but we were told the fan controller often is the problem. We also had the warm air when stopped, which cooled off again when up to speed.

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