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Post by Custom88 on Jul 16, 2006 18:41:43 GMT -6
I've noticed that when I turn my AC on, the car lags down HORRIBLY. I even notice a lag with just defrost on, and no AC oddly enough. Does anyone else notice a huge loss in power with their AC on? WHen I turn my AC on, my MPG drop by atleast 15 MPG and the car is almost unbearably slow. I have to accelerate at half throttle just to speed the car up decently. The air conditioning works great otherwise, besides the huge loss of power. I don't know what would cause this to happen, and I don't think it's normal because on both of our Bonnevilles I noticed NO difference at all when the Ac is turned on, and when it's off. The Aurora on the otherhand is nearly undrivable. I took it to the dealer just before my warranty was up, and they told me that the car was functioning 100% normal and nothing would be fixed. Occasionally, I will hear a rattling type sound from under the hood when the AC is on. It is not always there however. Any ideas? The video below shows how much power is lost from the engine when I turn the AC on/off. This was the best way I could find to show, because a video of the speedometer didn't really "show" what was going on, it was hard to tell a difference. By seeing the MPG gauge however, you can really see how much efficency is lost by using the AC. You can hear when I turn the AC on/off by the sound of the vent blowing onto my camera. I had the cruise control set at 50 MPH incase anyone was wondering what speed I was going. This was on a completely flat road, and the outside temperature was 97*. Let me know what you think. media.putfile.com/DSCN0525It is a quicktime video, so it will need to load 100% before it'll play.
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Post by Marc on Jul 16, 2006 19:34:14 GMT -6
There's usually about a 10% loss in HP with the A/C on, and a likewise drop in gas mileage. But from what you're talking about, I think that your 3.5 is showing a larger drop than that. My guess: I think that it would be a good idea to have it scanned. There's something wrong, and I think that the reason that the dealer said that everything was good was because they saw that the warranty was almost expired, and they figured that they could get out of doing warranty work by a little stonewalling. BTW, the A/C compressor works when you set the HVAC to the Defrost position.
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Post by A-boy95 on Jul 16, 2006 19:43:07 GMT -6
Yea there is a 10-15 Hp drop once you turn on the A/C
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Post by Custom88 on Jul 16, 2006 20:12:32 GMT -6
it feels more like a 50 HP drop on my car.. Like I said, on our 205 HP Bonneville, I notice no difference.. on my 215 horsepower Aurora, it struggles to accelerate.
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Post by Aurora40 on Jul 16, 2006 20:16:05 GMT -6
Maybe there's something wrong with the compressor? That's not normal...
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Post by unirok on Jul 16, 2006 20:45:02 GMT -6
We are well into summer so I ask....has it been this way all summer or have you not used the AC till now? Thats the thing I like about V8s there is almost no noticable difference AC on or off but thats my experience at least.
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Post by JimW on Jul 16, 2006 20:52:22 GMT -6
I notice a loss of HP as well, feels about 15-20% in the city, its not really noticed on the hwy. Dan, that loss seems a bit much as I seem to be echoing...couldnt hurt to check it out?
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BNICOV
Aurora Lover
Posts: 782
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Post by BNICOV on Jul 17, 2006 6:11:38 GMT -6
Don't forget too that in the extreme heat, the car is not running as efficiently ie. less power than in cooler weather.
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Post by centennialman on Jul 19, 2006 11:51:25 GMT -6
Just a long shot suggestion I'm sure, but is it possible that you have some kind of electrical problem such that the A/C circuit is interfering with the traction control circuit? If somehow TC is turning itself on, you sure won't get much acceleration.
EDIT - Now that I think about it some more, other causes of poor acceleration are failure of the spark advance system, and camshaft timing. I guess the computer controls spark advance, dont' know about camshaft - are they variable timing?
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Post by macadamiaman on Jul 21, 2006 16:51:23 GMT -6
Could be the 97º aspect of it as was said before - that's pretty freaking hot, so the car is struggling anyway. However, it's NOT normal. I have the exact same car as you, and I've been using it with AC for thousands of miles this summer - up to the low 90s - and no more than 10-15% loss in power. I've been up to 100-110mph on an 80º day with A/C on with no problem (though it would've been faster without A/C , so the car still accelerates fine, with noticable loss in power. However my compressor and complete system was brand new replaced @ 63k miles, so I'd say that that being the only different major variable, you have something wrong with your air conditioning system.
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Post by fast6cl on Jul 21, 2006 21:39:58 GMT -6
I wonder why no ones brought up the possibility of the ac compressor having shot barrings causing it to draw more power from the car ?
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Post by Marc on Jul 21, 2006 22:07:59 GMT -6
I guess the computer controls spark advance, dont' know about camshaft - are they variable timing? No.
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