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View Full Version : Does your Air Condition slows your car acceleration???


stso
10-02-2001, 03:04 AM
I'm driving 5-speed mustang, and it slows down my acceleration :Q

Edit: As requested, I'm driving 2000 5-Speed Mustang Coupe w/ 190 Horse Power. No money for the GT cus I'm a poor college student :|

Thread closed due to necro-bump.

Zenmervolt - AnandTech Moderator

yakko
10-02-2001, 03:05 AM
Yes.

Sluggo
10-02-2001, 03:05 AM
Your A/C creates an extra load on your motor, so simple physics would dictate that YES, there will be a corresponding performance drop.

Operating power windows during acceleration in some cars will produce a noticeable drop in power.

Unsickle
10-02-2001, 03:21 AM
<< Operating power windows during acceleration in some cars will produce a noticeable drop in power. >>


Those are some sucky cars. Electrical system designed by dummies? Hah.

dawks
10-02-2001, 03:29 AM
Yes it will. If you listen to your car while idleing, and turn on the A/C, you should notice the car's rpm increase, becuase the A/C compressor is taking more juice to turn it. Thats why its only on half the time, even when your A/C is running. Normally, you shouldnt have a problem with this... with standard everyday driving, but when ever it looks like I might be racing someone off of a stop light, I shut off the A/C ;)

It also takes more gas. As for the window issue, its not that big of a deal in most vehicles, but it is there. I dont think it would noticably affect your acceleration.. but I can hear my dads cars engine rev up when im lowering, or raising the windows.

Aihyah
10-02-2001, 03:32 AM
my civics accel is lousy i guess, so i don't notice it getting any worse with ac on:) course being comfy is better then being fast:)

Migroo
10-02-2001, 04:16 AM
I dunno, I don't have A/C

spanky
10-02-2001, 04:17 AM
my car has no acceleration...so i guess the answer would be no.

Jfur
10-02-2001, 04:21 AM
sure it will

Brian Mc
10-02-2001, 04:35 AM
You don't say which Mustang you have, but on mine (an SN95 GT) there is a relay that disengages the a/c clutch at WOT, so it's not really a problem.

Migroo
10-02-2001, 04:46 AM
<< You don't say which Mustang you have, but on mine (an SN95 GT) there is a relay that disengages the a/c clutch at WOT, so it's not really a problem. >>



nice idea :)

urameatball
10-02-2001, 06:02 AM
<< I dunno, I don't have A/C >>

my rollerblades don't have a/c either :(
but acceleration is already slow enough

Murpheeee
10-02-2001, 06:07 AM
I used to have a Mazda Protege 1999 model.
When the AC was off, the car ran very well.
As soon as you turned on the AC, it turned into a slug.
It was reaaly bad, I mean dangerous......when you try to merge onto a highway and you floor it to fit in a gap.....there was nothing there.

I took it back to the dealer a couple of times.....and they were like - what do you expect? its only a 4 cyl.
So I got rid.

My wife has an old Mazda 323......it runs very well, with or without AC.

vegetation
10-02-2001, 06:35 AM
Mostly affects 4 cylinder vehicles as they have little low end torque, so moving from a stoplight (normally) will cause a noticeable lack in acceleration ability. For instance, your 120 peak hp 4 cylinder only products like 40hp at 1000-2000 rpm, so the AC which eats up 5-6 hp, can be very noticeable. A V8, on the other hand, has a ample supply of power at the same rev range so the AC makes little differerence.

Some modern vehicles will shut the AC automatically if the throttle is applied fully, but this may take a few seconds to engage, so you'll still "feel the loss" for a second.

Freejack2
10-02-2001, 06:45 AM
On my Saturn I've noticed if I get up somewhere above 4000rpm it'll turn the compressor off.
Nice thing when heavy acceleration is needed.

downhiller80
10-02-2001, 06:46 AM
My dad's S6 turns the AC off when you use full throttle. Nice.

- seb

Viperoni
10-02-2001, 06:47 AM
actually the rpms would drop when it turns on due to the extra strain, but you'd have to rev higher to accelerate.
Also there's an AC solenoid that makes your idle a tiny bit higher if you're @ idle with AC on to keep the compressor running above it's minimum speed I suppose.

Bozz
10-02-2001, 06:47 AM
<< Yes it will. If you listen to your car while idleing, and turn on the A/C, you should notice the car's rpm increase, becuase the A/C compressor is taking more juice to turn it. Thats why its only on half the time, even when your A/C is running. Normally, you shouldnt have a problem with this... with standard everyday driving, but when ever it looks like I might be racing someone off of a stop light, I shut off the A/C ;) >>



That first statement is a paradox. What actually happens in virtually all modern cars is they have an auxillary air valve of some sort which bypasses additional air past the throttle butterfly to allow the engine to mildly increase idle speed which will also assist cooling and air con operation. This can easily be demonstrated by finding the valve that allows air past the throttle body into the plenum chamber and unplugging the wire(s) going to it. Switch the air con on and the revs will actually decrease since additional air/fuel cannot be automatically supplied to the engine, since the air conditioners compressor is slowing the engine.



<< It also takes more gas. As for the window issue, its not that big of a deal in most vehicles, but it is there. I dont think it would noticably affect your acceleration.. but I can hear my dads cars engine rev up when im lowering, or raising the windows. >>



The reason you hear that is because the alternator draws considerable power from the crankshaft of the engine, just like the air conditioner. It has NOTHING to do with a poorly designed electrical system in the car, it has more to do with the amount of torque the motor has at low RPM just like vegetation said. The difference is the alternator can draw about 2hp (for an 85 amp alternator = 13.8v x 85 amps = 1173w now subtract about 30% due to power & efficiency loss in belt, alternator and regulator which adds up to around 1.5kw, or just under 2hp). Operating your electric windows will result in power drain from the electrical system, which causes the alternator to produce more energy, which causes the engine speed to drop as it becomes more difficult to rotate the alternator, the ECU of the car will slightly increase engine speed etc etc etc....

Cheers

Bozz
10-02-2001, 06:48 AM
Doh! You beat me to it, Viperoni !!

Good to see another that knows his car stuff :)

Amused
10-02-2001, 10:47 AM
<< I'm driving 5-speed mustang, and it slows down my acceleration :Q >>



Good gawd, I must be old. Because all I'm thinking is, "YOU JUST FOUND THIS OUT????"

My father told me about this through his bitching and moaning about the loss of power when drove to go backpacking in Yosemite every year.

I think it's funny to see kids suddenly discover something that is common knowledge, and they think they've come upon a discovery so important, it rivals the ever elusive Unified Theory or something... :D

Like I said, I must be getting old.

Psychoholic
10-02-2001, 10:51 AM
<< You don't say which Mustang you have, but on mine (an SN95 GT) there is a relay that disengages the a/c clutch at WOT, so it's not really a problem. >>


This is true for any fuel-injected Mustang SN95 or even back to the Fox bodies. All engine sizes as well. As a matter of fact all fuel-injected Fords now have this. I can't speak for any other manufacturer, but I would assume they have somthing similar.

The only way this would affect acceleration is if something was malfunctioning.

Amused
10-02-2001, 10:54 AM
A compressor cutoff for WOT does little to help the change noticed in everyday driving. Very seldom, unless you're an idiot, does one use WOT to get started from stoplights and make a left turn through traffic. In these situations, the power loss from the AC must still be compensated for.

ShadowHunter
10-02-2001, 10:54 AM
<< Does your Air Condition slows your car acceleration??? >>



It does a little bit, enough to be noticeable but not really be bad. It more affects my idle, which is a little more rough with a/c.



<< I'm driving 5-speed mustang, and it slows down my acceleration >>



I would think a big phat V8 in that puppy wouldn't have any problems with a/c??

hungrypete
10-02-2001, 10:58 AM
it slows all cars down. AC = draw on motor = less HP.

Amused
10-02-2001, 11:03 AM
<<

<< Does your Air Condition slows your car acceleration??? >>



It does a little bit, enough to be noticeable but not really be bad. It more affects my idle, which is a little more rough with a/c.



<< I'm driving 5-speed mustang, and it slows down my acceleration >>



I would think a big phat V8 in that puppy wouldn't have any problems with a/c?? >>



My father always had big V8 buicks, Olds and full size Chevy conversion vans when we were growing up. The AC would bog those down too.

Viper GTS
10-02-2001, 11:09 AM
It slows down all vehicles, but it's especially noticeable if you have a weak engine.

For example, a Corvette Z06 is going to have a much less noticeable drop in performance than my Accord with less than 100 HP would.

Viper GTS

RambleOn
10-02-2001, 11:09 AM
Having the A/C on doesn't seem to make much of a difference in my truck, which is a 97 Chevy Silverado w/ a 350 V8. I think the engine is powerful enough so that the burden of the A/C isn't noticeable.

prodigy
10-02-2001, 01:03 PM
Yeah, I only have a 4 banger. I usually turn it off when I'm merging onto the freeway.

LAUST
10-02-2001, 01:18 PM
It doesn't slow down mine much at all for 2 reason's, one my system doesn't have a Radiator fan right now, and with the way it's been staying cool will prolly never have one... two, the SC is already making it's own load on the crank and that small little AC belt in comparison already doesn't mean squat to a motor that pumps out over 550lbs of torque :)

Eug
10-02-2001, 02:02 PM
On my hybrid (http://prius.toyota.com) the gas engine comes on more often when AC is on...

kendogg
10-02-2001, 02:05 PM
Yup on my integra gsr there is a noticeable decrease in power when the a/c is on.. I usually dont turn this sucker on unless its so HOT i cant take it.

it also eats your gas :|

Springzone
10-02-2001, 04:45 PM
Sure it does - That's why some old cop cars had kill switches when you floor it

mdennison
10-02-2001, 04:54 PM
Makes a huge difference on mine. I think car and driver should test cars with the a/c on too.

toant103
10-02-2001, 06:04 PM
YES

monto
10-02-2001, 06:05 PM
<< I dunno, I don't have A/C >>

ouch that sucks during summer...yes, stating the obvious

Jeff7
10-02-2001, 06:14 PM
Have a Hyundai Elantra; I don't notice a difference. It does up the rpm of the engine by about 50-100rpms, when I watch the engine meter while I'm idle.

stso
10-02-2001, 06:21 PM
bump original post edited!!

erub
10-02-2001, 06:23 PM
Mine does.

CandaceLeigh
07-24-2013, 07:07 PM
Yes in my car I've noticed that it does. I HAD a '06 Nissan Maxima fully loaded, now I have an '07 Maxima fully loaded. Okay. Well, in my '06 I never ever noticed it being an issue. I've only had my '07 for about 30 days and I am noticing a difference in the "get-up" on the acceleration and the difference between the AC being on or off. I'm hoping I don't have a weak engine, seeing as that I bought this car right out and don't have $$$ for big problems. --exhausted.

Bumping a thread that's OVER A DECADE OLD is bad form.

Zenmervolt - AnandTech Moderator

quakefiend420
07-24-2013, 07:11 PM
Yes in my car I've noticed that it does. I HAD a '06 Nissan Maxima fully loaded, now I have an '07 Maxima fully loaded. Okay. Well, in my '06 I never ever noticed it being an issue. I've only had my '07 for about 30 days and I am noticing a difference in the "get-up" on the acceleration and the difference between the AC being on or off. I'm hoping I don't have a weak engine, seeing as that I bought this car right out and don't have $$$ for big problems. --exhausted.

When this thread was relevant your Maximas were but a gleam in an engineer's eye....

Aikouka
07-24-2013, 07:29 PM
Yes in my car I've noticed that it does. I HAD a '06 Nissan Maxima fully loaded, now I have an '07 Maxima fully loaded. Okay. Well, in my '06 I never ever noticed it being an issue. I've only had my '07 for about 30 days and I am noticing a difference in the "get-up" on the acceleration and the difference between the AC being on or off. I'm hoping I don't have a weak engine, seeing as that I bought this car right out and don't have $$$ for big problems. --exhausted.

I'm pretty sure that Maxima model year came with a VQ35DE standard (the Maxima did get revamped in '08), which is pretty much Nissan's go-to V6 engine. You have plenty of ponies under the hood!

Also, congrats on your first post necroing a 12-year-old thread. :P

soccerballtux
07-24-2013, 08:06 PM
turn mine off turbo mode :sneaky:

Doppel
07-24-2013, 08:15 PM
I don't think it was always the case but certainly sometimes (maybe always now?) cars will turn off the AC under full throttle. Mine does this now and I know that because if I floor it, even after a few seconds I can feel the air get warmer.