AC sucking life out of engine?

[Colby]

I'm a big fan of summertime, but I hate running the AC in my Jeep. Everybit of power gets sucked out of the engine. Has anyone overcome this problem? Does someone make an underdrive pulley kit for the 4.0? My Jeep is a 95 XJ 4.0 5spd with 72k miles. The only engine mods I have are a Turbo City air tube w/ K&N filter. There must be something I can do without spending thousands of dollars. Thanks,

Colby

[Rev Den]

Yup...there is something you can do.....


http://home.attbi.com/~denjeep/pic/day3.jpg

Never use the A/C.


Rev

[andyr354]

On my 98 I can hardly tell the AC is running when driving down the road. It is completely stock. Are you running larger tires that are allready sucking power? Maybe you need to look at regearing.

[Colby]

I'm running 31s with stock gearing which definitely contribute to the power problem Regearing might be the best (only?) option.
Colby

[andyr354]

you said that you have a 5spd, so you might have 3.07 or 3.55 gears. If you have 3.07 ratio you could go salvage yard hunting for axles with the 3.55. If you already have 3.55, 4.11 is a little larger jump with only 31's. Maybe somebody else with that combination will chime in and say how they like it.

Have you looked into all the other possibilities. Give it a full tuneup with cap, rotor, plugs, and a can of good injector cleaner?

[GSequoia]

I'll give you this much:

'89 with Auto, 3.55:1 ratio, stock AC system, I don't notice any sort of power loss with my AC either.

That's on 235/75/15 tires.

[Eagle]

I have an '88 5-speed 4.0L with 235,000 miles. Running the a/c makes no discernable difference, either seat-of-pants or in highway gas mileage.

The a/c does not "suck the life" out of the 4.0L. If you have a 5-speed then you have 3.07 gears, and with 31" tires THAT's what's sucking the life out of your 4.0L. 3.07 isn't enough gear with stock tires, and the 31's drop the RPMs for any speed by another 10 percent. At 65 miles per hour your engine is only turning about 1400 RPM -- that's barely more than idle speed.

31s with 3.73 gears match the final drive ratio of stock tires and 3.54 gears exactly. Sounds to me like you really need 4.10s.

[Ralph]

I too can tell a big difference with my A/C running. I'm running 4.0/auto/31's with 4.10's. Unless it's really hot, I don't run the A/C.

RR3

[Kevin]

I have the same problem with my '95. Maybe its a problem with the particular model year. I notice that whenever the fan on the condenser coil at the radiator energizes is when I experience the greatest loss of power and the engine whines. I've adopted the "don't look and maybe it will go away" policy, but that has not seemed to work. Things are also worse now that I'm running 31s with stock gearing.

[brtb]

'88 base model with a 4.0L, AW4, 215/75/R15 stock-size (AFAIK) tires; AC does put some drag on it, not sure if I'm already down on the power (AFAIK again, this thing's still got the stock cat and who knows what else too, probably not helping much) or if I'm just being too critical.... I don't think I've ever pushed the gas pedal further than 1/2 way down - having no tach scares me :D

[Eagle]

Originally posted by brtb
'88 base model with a 4.0L, AW4, 215/75/R15 stock-size (AFAIK) tires;

Man, you don't seem to realize that you own a HIGHLY modified Jeep :D

The stock tire size for an '88 base model (or a Pioneer, for that matter) was 195/75R15. The mandatory "upgrade" if you opted for the 20-gallon fuel tank was a huge 205/75R15. Your tires are so much bigger than stock I'm surprised you can drive without an oxygen mask.

[Boz88xj]

Dude eagle, my tires have a stock 225/70 R15.... hehe actually thats just what was on int when we got it from the dealer used.

Damn, im big pimpin now, next stop foedee foes!

[eric91xj]

I have a '91 xj with an auto and 225/70/15 radial t/a's with numerous engine and body lightening mods and i must say i've been considering taking out the a/c and finding a shorter serpentine belt for it cause i hate the a/c as i see it drain a ton of power from the motor too

Eric

[SV1CEC]

It's funny how some of you gentlemen are complaining about the A/C robbing you of power, with those 4.0 lt engines, with anything between 180 and almost 200 bhp). I think you are spoiled!

In Greece, cars with engines larger than 2.0 lts, are almost forbidden by taxation laws, unless you are a tycoon. So I would invite you to drive either my '84 Cherokee with the anemic, carburated 2.5 lt engine, or my Ssang Yong Musso, with its equally anemic 2.0 lt Mercedes engine (135 bhp with almost 1,900 kgs of weight) and turn on the A/C. Then, you will know what "sucking power from my engine" means.

Rgds

[WrenchMonkey]

:patriot:God bless the USA!!! :patriot:

[88justin]

88, 4.0l, 5sp, 3.73, 31", replaced the entire AC .....still feels like a dog with the AC on.

it does however keep my 1500rpm high idle problem at bay! with the AC on its just at 1000rpm!

[Eagle]

Originally posted by Boz88xj
Dude eagle, my tires have a stock 225/70 R15.... hehe actually thats just what was on int when we got it from the dealer used.

"Stock" is what was sold by the factory, not Joe the Gyp's Used Car and Bike Emporium. Jeep never used any 70-series tires on the XJ until they started using 16-inch rims in 2000. Any 15-inch 70-series tire was definitely not "stock"

[jalehman]

My '96 with a 4.0 litre has a huge loss of power with the a/c running. Every car I've owned has had a little loss in power, but not near as much as my jeep.

[brtb]

Originally posted by Eagle
Man, you don't seem to realize that you own a HIGHLY modified Jeep :D

The stock tire size for an '88 base model (or a Pioneer, for that matter) was 195/75R15. The mandatory "upgrade" if you opted for the 20-gallon fuel tank was a huge 205/75R15. Your tires are so much bigger than stock I'm surprised you can drive without an oxygen mask.

195's stock? And I thought the 215's looked small compared to the other Jeeps in the parking lot :D

Oh yeah, this thing's all modded out. Zero factory options apart from the 4.0, AW4 and 20-gal gas tank. 215 tires (which don't seem to mess with the speedometer any), really crappily-wired (think loosely twisted together wires with masking tape... fixed that already) CD player hooked to what looks like pro-installed speakers in the front doors (yeah I know there aren't supposed to be door speakers), remnants of a Radio Shack car alarm I ripped out, $20 Autozone muffler, badly installed shift-interlock-recall device.

Probably all-original everything else, including the stupid no-tach instrument panel, very old-looking but not rattling cat and who knows what else hasn't been replaced. Emissions timer was unplugged so who knows how long it's been like that. Owner before me was a college student who probably fancied himself an electrical engineer and mechanic but was far from it. At least it's had regular oil changes...

Gets 18-20mpg city and it's not _too_ loud so I'm not messing with it. Too much. :angel:

[wascobi]

4.0 with 31's and 3:73 gears. 5 speed. when my air kicks on it almost sends you through the windsheild!wonder if its a compressor fault of somekind?

[ThePhantum]

'97, 4.0HO, AW4, 3.55's and 30's. I barley notice the A/C being on. The only time it becomes apparent is during hard acceleration...and even then it still gets out of it's own way.

The MPG's go down a little when running it...from 19-21 to about 17-19.

[Tom R.]

Originally posted by Eagle
"Stock" is what was sold by the factory, not Joe the Gyp's Used Car and Bike Emporium. Jeep never used any 70-series tires on the XJ until they started using 16-inch rims in 2000. Any 15-inch 70-series tire was definitely not "stock"
I'll almost (must confirm, but fairly certain) bet you Eagle that Jeep did, in fact, use 70 (aspect ratio) tires.....at least on the XJs with Upcountry package. I'm 99.9% sure my XJ w/ Upcountry came stock with 225/70/15 tires. What do say if you lose this wager that you'll promise to make it out to Moab next year? And if I lose the wager, you'll still come out to Moab next year? Okay, it's a deal. :D

Tom

[Tom R.]

Oh, I forgot to mention......in my first XJ, which was a cherry '89, 4.0L, AX-15, low mileage and very good runner, that I could notice a huge difference in power when running the AC. Fast forward to my current XJ, a '92, auto, 32" tires, 4.56 gears, etc. I can still notice a difference, even when it was stock, but it's not as great of a power loss as my '89. What really helps is keeping the RPM around 2500 or higher. That's when I don't notice it quite as much.

BTW, I owned a Honda Civic in '85-86 that when I put on the AC the only thing you'd notice is that the inside of the car got cooler. No effect on power. I've always thought the XJs I've own lost too much power when using the AC.

Tom

[Dr. Dyno]

Originally posted by SV1CEC
It's funny how some of you gentlemen are complaining about the A/C robbing you of power, with those 4.0 lt engines, with anything between 180 and almost 200 bhp). I think you are spoiled!

In Greece, cars with engines larger than 2.0 lts, are almost forbidden by taxation laws, unless you are a tycoon. So I would invite you to drive either my '84 Cherokee with the anemic, carburated 2.5 lt engine, or my Ssang Yong Musso, with its equally anemic 2.0 lt Mercedes engine (135 bhp with almost 1,900 kgs of weight) and turn on the A/C. Then, you will know what "sucking power from my engine" means.

Rgds

Yia sou Yianni. Ti kaneis? I'm of Greek-Cypriot descent and a regular visitor to Cyprus. It's the same over there too. Only the stinking rich or corrupt politicians can afford to own cars with engines over 2.0L. Most cars in Cyprus have small 1.3-1.6L four bangers.
I'm spoilt over here driving a 4.0L Cherokee and even luckier that gasoline is so cheap (it's cheaper than water here!). In Saudi Arabia, only a small minority of cars have an engine of less than 2.0L. I only notice a slight loss in performance when I'm using the A/C and I put that down to having a big engine that has several performance mods.