I have a 2008 Honda Civic Si and it runs great. But, whenever I'm driving at about 6mph - 20mph with the AC on, I can feel a drag in the engine (power loss) whenever the AC compressor engages. The drag only lasts as long as the compressor is in engagement. I also want to note that the AC compressor works fine with no noise or other visible problems.

I've had this concern ever since I owned the car some 2 years now. It's annoying and doesn't seem like the normal behavior. Any help/diagnostic would surely be appreciated. Thanks

  • Hi and welcome. The A/C compressor is a horsepower-stealing beast. So, clearly, small engines are the most vulnerable. It may be totally normal for your car. What engine do you have?
    – mike65535
    Dec 19, 2018 at 18:02
  • I'm aware the compressor does that but I didn't think it would to be that noticeable. My car has a K20Z3 engine, which is a 2.0 litre. Dec 19, 2018 at 19:41
  • If you experience too low/uneven idle rpms or electricity failures then it could be an issue with how the A/C compressor pulley rotates when the A/C is turned on, otherwise it's probably normal.
    – Lukas G
    Dec 20, 2018 at 2:17
  • I have the same engine and I honestly beg to differ. I've never noticed this while accelerating, and I'd also say 2L isn't exactly too small to drive AC smoothly - plenty cars on the road have similar displacements. When you say you can feel a drag, what exactly do you mean? Does it actually lurch forwards slightly once the compressor engages? Is this at part throttle, full throttle, very light throttle? Why doesn't it happen at higher speeds? Unfortunately I'm not familiar enough with AC to give a good answer, but I wouldn't dismiss this as normal just yet. Dec 20, 2018 at 15:28
  • Yes, it lurches forward slightly once the compressor engages and it occurs at very light throttle, probably at 2500 - 3000 rpm Dec 24, 2018 at 16:13

1 Answer 1


This sounds normal. A/C robs power from the engine. You will feel a slight decrease in power and fuel efficiency. @mike65535 also stated this in a comment above. you have a small engine, so you will definitely feel it more. I am pretty sure those k-series motor shine at higher rpms anyways (v-tec).

I don't think this is anything to be concerned about, unless you are experiencing other symptoms, such as the air isn't as cold as it should be.

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