HELP - car's power different when AC is on

dirtyred11

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Ok guys just a quick question, so I was driving one day and it was kind of hot out so I let up the windows and turned on the A/C. The car began to feel totally different. Im not sure about the rpm's but I know that the power was different and it affected everything about the car. So if one of you guys have had this happen to you and you solved this problem could you please shine some light on this subject or if someone just knows what it is that would be great too. Thanks in advance for all the help.....
 

TanTop94

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^^^ What he said....my car feels very different when I turn on a/c. Im so picky about having it on because of what it does to my car.
 

CC'S95GT

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The A/C compressor might be going bad and causing extra load on the engine.
Or the IAC isn't opening to allow the engine to "idle up" when the a/c is on.
 

dirtyred11

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The A/C compressor might be going bad and causing extra load on the engine.
Or the IAC isn't opening to allow the engine to "idle up" when the a/c is on.
That's what I was thinking it was the iac, I was gonna probably change it this weekend and pick up the part from a local autozone. And I've also heard that it could be the a/c compressor but I hope not.
 

96blak54

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I always thought flipping the a/c on altered the timing tables too. If their is a bad oxygen sensor, the altered timing curves are basically useless because of fuel and air mixture being poopy.
A bad sensor dont always show up as a check engine light either. The sensor may be cutting on and off rapidly but staying on enough to show the computer signals. The easiest way to tell a fault sensor is reduced fuel mileage. And with a/c off, the engine has a slight sluggish stall when rolling the throttle in to WOT but once the throttle is opened enough the engine has a quick pick up in power. Almost like the car was struggling to pull something but then lost the load ....kina feel
 

dirtyred11

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I always thought flipping the a/c on altered the timing tables too. If their is a bad oxygen sensor, the altered timing curves are basically useless because of fuel and air mixture being poopy.
A bad sensor dont always show up as a check engine light either. The sensor may be cutting on and off rapidly but staying on enough to show the computer signals. The easiest way to tell a fault sensor is reduced fuel mileage. And with a/c off, the engine has a slight sluggish stall when rolling the throttle in to WOT but once the throttle is opened enough the engine has a quick pick up in power. Almost like the car was struggling to pull something but then lost the load ....kina feel
This does sound like some of the problem that I am having with mine now, so are you confirming that I need to look into the IAC or suggesting look into my o2 sensors or some other sensor? And I was thinking that I wasn't getting the best gas mileage and yes I know that comes with the territory and who cares about that to a certain extent, BUT.... still its the point.
 

nightfire

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I always thought flipping the a/c on altered the timing tables too. If their is a bad oxygen sensor, the altered timing curves are basically useless because of fuel and air mixture being poopy.
A bad sensor dont always show up as a check engine light either. The sensor may be cutting on and off rapidly but staying on enough to show the computer signals. The easiest way to tell a fault sensor is reduced fuel mileage. And with a/c off, the engine has a slight sluggish stall when rolling the throttle in to WOT but once the throttle is opened enough the engine has a quick pick up in power. Almost like the car was struggling to pull something but then lost the load ....kina feel

No, no, and no. Just no. Please tell me you're new to automobile mechanics.

Jesus Christ people, your cars performance has NOTHING to do with the AC being on or off. Only ricers complain of AC performance loss
 

96blak54

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Dont get me started on my good friend Jesus.....you brought him up.

Anyhow perhaps you should reread my post because it has nothing to do with a/c on. Its obvious your comprehension skills need improving as well as the anger in your heart.....thats what Jesus is for.
 

dirtyred11

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No, no, and no. Just no. Please tell me you're new to automobile mechanics.

Jesus Christ people, your cars performance has NOTHING to do with the AC being on or off. Only ricers complain of AC performance loss
Im not saying that the cars performance is different, but that the car just feals and drives differently when it is on and since I am new to the 4.6 I wanted to know if this was normal or not.
 

Goldmember

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I notice the difference especially when it's 90 degrees and the car is heat soaked. Just how they are. Some of us call it the V6 Tune
 

dirtyred11

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Ok guys I was messing around with the car tonight and went ahead and threw on a new IAC just to see what improvements it would make because my idle had been acting wacky all day even when I just turned on the defrost. Well I put it on and turned on the defrost and raised the hood to see what was going on. I noticed that when the car surged the a/c compressor (or whatever the technical term is) would sort of engage then stop suddenly and would keep doing this. It would spin and then stop, just to clear that up if I worded it wrong. So I need to know is this the root of the problem I've been having all along. O yea, and I didn't notice a real difference in anything with putting the new IAC on.
 

nightfire

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Dont get me started on my good friend Jesus.....you brought him up.

Anyhow perhaps you should reread my post because it has nothing to do with a/c on. Its obvious your comprehension skills need improving as well as the anger in your heart.....thats what Jesus is for.

I reread you post. Aside from the various grammatical errors, there is nothing that needs any more "comprehension". The a/c on full-blast draws maybe 2-3HP off the motor. Unless you can honestly notice a 2-3hp difference, then the ac has nothing to do with the "sluggishness" you're feeling. Also, the operation of the ac has absolutely ZERO effect on other ECU parameters. This is such a ridiculous discussion.
 

DeepList

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I reread you post. Aside from the various grammatical errors, there is nothing that needs any more "comprehension". The a/c on full-blast draws maybe 2-3HP off the motor. Unless you can honestly notice a 2-3hp difference, then the ac has nothing to do with the "sluggishness" you're feeling. Also, the operation of the ac has absolutely ZERO effect on other ECU parameters. This is such a ridiculous discussion.

First of all, you need to simmer down a bit. And second... 2-3 hp? Seriously?

The air conditioner takes mechanical power away from the engine. The blower takes electrical power from the alternator, then the alternator itself takes a bit more mechanical power. I think at highway speeds, the air conditioner takes approximately ten percent of the car's power to run. At idle, it would be significantly more... maybe a third? When the AC is on, the ECM compensates for the additional load by richening the mixture, adjusting idle control flow and injector firing. It's pretty common knowledge that running the AC robs away a significant amount of the car's power. Hence why Goldmember pointed out that we call it our "V6 Tune" :p

If you really think there's something wrong, a couple of things to check for:
- Alternator issues
- Worn out or faulty AC pump, maybe a bearing or seal going out
- Dirty IAC (which you've already ruled out)
- Loose belt

That's all that I can think of right now. But from the way you describe what's going on, it really sounds about typical.
 

96blak54

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Thank you deeplist!


Please tell me you're new to automobile mechanics.

Jesus Christ people, your cars performance has NOTHING to do with the AC being on or off. Only ricers complain of AC performance loss

Your knowledge is appreciated, but your anger is not. Post all the knowledge you want,.... please do not use derogatory quotes and/or terms. Offer your intelligence in a positive manner please....lol.
 

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