why does the a/c drain power - Dodge Dakota Forum

Subject: why does the a/c drain power
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i don't know if you v6 and v8 guys notice it, but when i turn the a/c on in my 2.5l, i lose a lot of throttle response. it is so noticible on the freeway. with the a/c it takes for ever to go from 55-60 in 4th, but with a/c off it does it in almost half the time. what is up with that?

Walter
Dodge Dakota
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6/10/2003
07:30:07

RE: why does the a/c drain power
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Over the years I've been driving the 4 banger is the worst for running A/C. I had a van that was a v6 and even in it I could tell when I had the A/C on or not buy the pick-up it did or didn't have. But just in case there is something else wrong maybe you should get it checked out. It would help to if we knew how old your truck is.

BigBlue QC
GenIII

6/10/2003
07:57:13

RE: why does the a/c drain power
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the A/C compressor requires a good chunk of power to run and keep running. When the A/C is on, the power has to come from somewhere and since the engine is making all the available power for that vehicle something has to give. Since a 6 or 8 cylinder makes power easier than a 4, hence the reason why it is much more noticable in your 4 cylinder.

2002 QC 4x4 Sport Plus, 4.7L, auto, Patriot Blue, Tire & Handling group,
Heavy Duty Service group, Leer cap w/out windows, Mopar Step bars and roof rack, Rhino liner in bed and on step bars, Pace Edwards Power Tailgate lock
3.55 rear, 4-wheel anti-lock brakes, all possible fluids are AMSOIL

nate
Dodge Dakota
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6/10/2003
08:41:51

RE: why does the a/c drain power
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I have the same problem when I am trying to go up a hill. I mean, it takes forever. But on flat land, it doesnt take that long. But hey, downhills are great.

ps-you should have some sort of resemblence of knowing what the hell is going on under the hood of your car before you are allowed to drive.

Fargo
Dodge Dakota
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6/10/2003
10:36:05

RE: why does the a/c drain power
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You also ahve to remember the overall design of the AC system. Not only does it put a higher load on the engine, but it also heat soaks it. Usually when you're using your AC it is hot. Once you turn on your AC, your compressor is pumping all of the heat from your cab to dirrectly in front of your radiator significantly increasing the temperature of your engine compartment and reducing your cooling system's ability to function efficiently. More heat and more drag = lots of ponies down the drain.

00287RC
Dodge Dakota
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6/10/2003
12:13:47

RE: why does the a/c drain power
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your AC compressor is turned by a pulley just like all of your other accesories. It takes power to turn the pistons in that compressor and that power comes from your motor. I dont know about Dodge but many cars, Ford Mustangs for instance, will disengage the AC clutch at wide open throttle.

RaZoR1
Dodge Dakota
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6/10/2003
16:13:59

RE: why does the a/c drain power
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Yep....... I have a V8 and still notice it. Roughly eats about 10-20 horses. That's why some guys decrease the size of their pulleys to make more power.

00287RC
Dodge Dakota
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6/10/2003
17:10:35

RE: why does the a/c drain power
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never heard of decreasing the AC pulley size

Squirrel Cage
Dodge Dakota
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6/10/2003
19:23:46

RE: why does the a/c drain power
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I heard that on a 2.5 l it takes 1-1/2 cyl's to run the air, leaving you 2-1/2 cyl's to run the truck ?

I could have had a V8

93Dak
Dodge Dakota
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6/10/2003
20:27:08

RE: why does the a/c drain power
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For an underdrive pulley system, the crank pulley is decreased while all the others are increased to create less drag.

00287RC
Dodge Dakota
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6/10/2003
20:30:36

RE: why does the a/c drain power
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no, it doesn't take 1.5 cylinders to turn the AC compressor. It only takes a few horsepower from the motor. Sandens don't have a lot of displacement compared to others like the old 2cyl cast iron RV2. Sure you're going to notice more power loss in a 2.5 than a 5.9 because it makes less power to begin with.

and the size of your AC pulley doesn't matter much because when your AC is on it's pumping the compressor, when it's off its not, just spinning the clutch pulley...the clutch itself is not engaged. Plus there are not a readily amount of interchangeable AC clutches out there unless you know people like me. Now taking the entire AC out will make a difference (less weight, 1 less pulley).

Scott
Dodge Dakota
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6/11/2003
18:58:40

RE: why does the a/c drain power
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When your AC is engaged it draws quite a bit of HP. You can buy vacuum or throttle position switches that cut out the AC clutch when you wan tto accelerate (if Dakotas do not have something already). The size of the pulley will definitely have an effect on the power and performance of your AC. Bigger pulley draws less power (simple torque calculation), but also slows down your AC compressor.

Scott

00287RC
Dodge Dakota
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6/11/2003
22:48:53

RE: why does the a/c drain power
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if you want to accelerate just turn your AC off, lol.

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