How much horsepower does it take to run A/C?

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Yeah. There is a valve actuated by the suction pressures that in turn varies the pressure in the compressor crankcase. More crankcase pressure reduces the angle of the wobble plate acting upon the 5 pistons, shortening their stroke.

Modern compressors like that can vary from 125-150cc displacments all the way down to ~25-30cc when demand is low, reducing load on the engine and on some systems eliminating the need for a freeze protection mechanism for the evaporator.

As far as still seeming sluggish, the OHV 2.0/2.2's breathing at upper RPM was not the strongest anyway. The ECM was usually still setup to disengage the clutch at near WOT or 6000 RPM (IIRC) also.

OTOH, the same basic A/C setup is in my Quad 4/5-speed Olds, and the power loss is very small in it.
 
Hah, well I have only really driven it for a week (and put 250 miles on it since then Lol) but the A/C has been on for most of it. Its been pretty [censored] hot and muggy here. One of the cooler days I'll run it with A/C off to see the difference. But it runs really smooth and acceleration is smooth, albeit a bit slow and racous. One of these days I'll do a 0-60 run video to show off just how slow my car actually is! Hehe.
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No noticeable power loss in my Jeep. Fuel economy actually goes up when I use the A/C. Just the click of the compressor cycling.
 
Originally Posted By: rudolphna
But it runs really smooth and acceleration is smooth, albeit a bit slow and racous. One of these days I'll do a 0-60 run video to show off just how slow my car actually is! Hehe.
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The OHV 2.2 is not bad at all in a Cavalier IMO. There have been many compacts before it way slower.

Now a 2.2 automatic S-10 or Sonoma on the other hand, seems peppy in city driving, almost tapped out merging into a fast moving freeway.
 
Originally Posted By: CharlieJ
I guess when driving a 4-banger the power decrease is much more noticeable compared to a 8 or even a 6 cylinder car with twice the power. My next car needs a bigger engine.
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I don't notice much power loss or drop in fuel economy penalty in my Mazda3 when using the A/C on the highway, but it really makes the drive-by-wire throttle lag when driving in the city (as if it wasn't bad enough to begin with). I almost never use A/C for city driving, but I used it once when I had my mother with me while driving through Calgary to a wedding and it was terrible. I wouldn't recommend this car for anyone who uses A/C in city driving.
 
My 2.5 jeep will alter speed a good bit with AC cycling ..as it will with grade. I don't have cruise control and it makes it a real pain for someone following you trying use you as a pace car so they can numb out. I just did an electric fan conversion ..and I really think it made it more pronounced. I no longer have a few pounds of rotating mass to mask it as much.
 
Yes, it is. Its running over 5000 at the 108mph limiter. (btw, which I do not recommend testing, the steering is very light, with the pump running so fast.)
 
A 5-ton home unit will cool a 2400 sq foot house in 100F weather. It uses 8hp. That house has 10x as much glass as your typical car although the home is better insulated. I can't imagine any car AC using more than 5hp
 
Originally Posted By: BuickGN
I keep wondering if something is wrong with my TL. With the AC running it will hardly get out of it's own way. During acceleration from a stop to 65mph I can feel every time the comperssor cycles. It's so bad I keep thinking it's trying to freeze up and I'm worried about breaking the belt. I turn it off sometimes until I'm up to speed.

I would sell the TL if it was mine.

With the Ford Crown Victoria I see no difference in performance weather its on or off. We just leave ours on all the time all year long.
 
Originally Posted By: Onmo'Eegusee
Yeah, I just leave it on Automatic with 74-76F temperature year round.

Thats exactly the same temperature we set it on.
 
I believe I read somewhere once that 2-ton is the approximate capacity of a typical passenger car's A/C.
 
Originally Posted By: Onmo'Eegusee
Yes, it is. Its running over 5000 at the 108mph limiter. (btw, which I do not recommend testing, the steering is very light, with the pump running so fast.)


That's the only thing i hate about my wife's 01 is the 3 spd. I give it credit though. it can still turn almost 27mpg with it. With 120K on the clock, I've been tempted to install a new OEM 02 to see if mpg will improve.

I got her AC going again a few weeks ago after it hadn't been working for over a year. turns out the shaft seal in the compressor was bad. Leak dye didn't show up until after refilling it two times. Luckily I found it before digging into the dash to do the Evaporator. I learned my lesson about the reman AC comp, and found a Autozone that had a new OEM Delphi in stock. The reman (wanted new anyways) Ready-Aire only lasted 15 minutes then it blew the shaft seal. It didn't sound right from the get go after filling it with oil, but I had my fingers crossed.

It blows ice trucking cold now with new orifice tube, condenser, drier, and Comp :)
 
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