disable auto a/c

cjr1881 · 06-02-2012, 10:06 AM

Quote:

Originally Posted by Ubetit

My 4 ton home Ac unit pulls 14500 watts... roughly 19 horsepower. 3 horsepower won't run a 4 ton AC compressor but I don't see our little car ac compressors pulling much more than a standard window AC unit that pulls between 2-3 horsepower or 2500-2300 watts depending on BTU rating.

2-3hp would be unnoticeable. Rpms go up at idle and I hear a big difference in my exhaust note when driving as my engine is more labored. If you are in touch with your vehicle's behavior at all you will notice lack of power and it is definitely present. I know when I feel sluggish I look down and sure enough the a/c is on. I wouldn't notice if it were only 2-3 hp. Searching on the net I have seen figures 5-15. I think our cars are on the high side or I am just very sensitive to noticing power change.

ChrisSlicks · 06-02-2012, 10:48 AM

I've used my A/C on track several times to keep the windshield defogged in misty conditions. There was no difference in car feel, acceleration or lap times. An auto A/C compressor isn't quite as efficient as a home unit but the comparison isn't that far off. Power is power as was stated, the difference is in a direct drive compressor you will feel the drag more than the power loss (flywheel effect) and in the low rpm range where the car isn't making much power. At most it pulls 5hp when active and it does seem to disengage under WOT. You'll notice 5hp in a 100hp car, but not so much in a 300hp car.

'10Anamoly · 06-02-2012, 11:17 AM

I'm pretty sure the car has different ECU maps for use when the A/C compressor is on. The power you feel come back during WOT is the car switching maps. The timing, idle speed, etc are very different when the A/C compressor is on. Thus, who knows what power you do or dont lose, but its true that the compressor itself doesnt take up 15 hp.

KaienZ34 · 06-07-2012, 08:37 PM

Quote:

Originally Posted by ChrisSlicks

I've used my A/C on track several times to keep the windshield defogged in misty conditions. There was no difference in car feel, acceleration or lap times. An auto A/C compressor isn't quite as efficient as a home unit but the comparison isn't that far off. Power is power as was stated, the difference is in a direct drive compressor you will feel the drag more than the power loss (flywheel effect) and in the low rpm range where the car isn't making much power. At most it pulls 5hp when active and it does seem to disengage under WOT. You'll notice 5hp in a 100hp car, but not so much in a 300hp car.

From a man that has used his z on many track events, lap times don't lie.

Compdoc777 · 06-02-2012, 12:50 PM

Quote:

Originally Posted by cjr1881

2-3hp would be unnoticeable. Rpms go up at idle and I hear a big difference in my exhaust note when driving as my engine is more labored. If you are in touch with your vehicle's behavior at all you will notice lack of power and it is definitely present. I know when I feel sluggish I look down and sure enough the a/c is on. I wouldn't notice if it were only 2-3 hp. Searching on the net I have seen figures 5-15. I think our cars are on the high side or I am just very sensitive to noticing power change.

If the ac compressor is overfilled it can cause a drag on the system when it's on.

MattP725 · 06-01-2012, 04:02 PM

Also keep in mind that the AC will disengage when you hit WOT. Really step on the gas and feel the vents... the air gets almost instantly warmer for a minute.

Otherwise as others suggested take it off auto... I tend to think it is not always engaged because even when heat comes from the vents the AC light never goes off.

Also no way you are losing 25 hp...

'10Anamoly · 06-01-2012, 04:10 PM

I too would like to be able to set my vent to recirculate without having to run the A/C, which our cars do not allow.

spearfish25 · 06-01-2012, 09:07 PM

Quote:

Originally Posted by '10Anamoly

I too would like to be able to set my vent to recirculate without having to run the A/C, which our cars do not allow.

Your car will turn into a rainforest and get foggy mighty quickly.

KaienZ34 · 06-06-2012, 10:22 AM

Quote:

Originally Posted by cossie1600

You wont see jackshit on the dyno because the AC shuts off when you go wot. 3HP can run a 4 ton compressor.

Quote:

Originally Posted by MattP725

Also keep in mind that the AC will disengage when you hit WOT. Really step on the gas and feel the vents... the air gets almost instantly warmer for a minute.

Otherwise as others suggested take it off auto... I tend to think it is not always engaged because even when heat comes from the vents the AC light never goes off.

Also no way you are losing 25 hp...

On very old cars 1980's and older the AC did not kick off when you went WOT all newer cars do.

cjr1881 · 06-07-2012, 07:46 PM

Quote:

Originally Posted by KaienZ34

On very old cars 1980's and older the AC did not kick off when you went WOT all newer cars do.

It doesn't really matter to me that it disengages at WOT. I don't know about you guys, but I don't just want power when I am going in a straight line. If you feather the gas pedal in a corner, and even if you do go full throttle, it takes time for it to disengage. You guys that don't think it matters are just not race minded and aren't real drivers.

KaienZ34 · 06-07-2012, 08:22 PM

Quote:

Originally Posted by cjr1881

It doesn't really matter to me that it disengages at WOT. I don't know about you guys, but I don't just want power when I am going in a straight line. If you feather the gas pedal in a corner, and even if you do go full throttle, it takes time for it to disengage. You guys that don't think it matters are just not race minded and aren't real drivers.

Please for the love of god pay for a day on a dyno and see what very little hp you loose from your ac and report back. Since you know all in this world and the next about racing and cars in general. If you know so much why would you be asking anyone anything since they are all inferior beings? Do tell us, we all need you to guide us in your ways O'Lord internet racing. Have you ever even been to the track or done any HPDE events??

cjr1881 · 06-08-2012, 06:17 AM

Quote:

Originally Posted by KaienZ34

Please for the love of god pay for a day on a dyno and see what very little hp you loose from your ac and report back. Since you know all in this world and the next about racing and cars in general. If you know so much why would you be asking anyone anything since they are all inferior beings? Do tell us, we all need you to guide us in your ways O'Lord internet racing. Have you ever even been to the track or done any HPDE events??

I asked how to disable auto a/c, not whether it bothered you guys or not.

bdavis89 · 06-07-2012, 10:17 PM

Quote:

Originally Posted by cjr1881

It doesn't really matter to me that it disengages at WOT. I don't know about you guys, but I don't just want power when I am going in a straight line. If you feather the gas pedal in a corner, and even if you do go full throttle, it takes time for it to disengage. You guys that don't think it matters are just not race minded and aren't real drivers.

Sounds like you made a mistake by buying a car with a/c? After all, real race cars don't have a/c..

cossie1600 · 06-07-2012, 10:21 PM

b1adesofcha0s · 06-08-2012, 09:57 AM

Quote:

Originally Posted by cjr1881

It doesn't really matter to me that it disengages at WOT. I don't know about you guys, but I don't just want power when I am going in a straight line. If you feather the gas pedal in a corner, and even if you do go full throttle, it takes time for it to disengage. You guys that don't think it matters are just not race minded and aren't real drivers.

06-02-2012, 10:48 AM	#2 (permalink)
ChrisSlicks A True Z Fanatic Join Date: Mar 2009 Location: North East Posts: 6,203 Drives: 09 370Z Sport M6 Rep Power: 653	I've used my A/C on track several times to keep the windshield defogged in misty conditions. There was no difference in car feel, acceleration or lap times. An auto A/C compressor isn't quite as efficient as a home unit but the comparison isn't that far off. Power is power as was stated, the difference is in a direct drive compressor you will feel the drag more than the power loss (flywheel effect) and in the low rpm range where the car isn't making much power. At most it pulls 5hp when active and it does seem to disengage under WOT. You'll notice 5hp in a 100hp car, but not so much in a 300hp car. __________________ Hotchkis ARB \| Stillen CAI \| Art Pipes \| Berk CBE \| Stillen AP Racing Brakes \| AE Performance Oil Cooler \| BC Racing ER Coilovers \| Doran Control Arms

06-02-2012, 11:17 AM	#3 (permalink)
'10Anamoly Track Member Join Date: May 2010 Location: GA Posts: 882 Drives: 2010 370Z BS M6 Rep Power: 16	I'm pretty sure the car has different ECU maps for use when the A/C compressor is on. The power you feel come back during WOT is the car switching maps. The timing, idle speed, etc are very different when the A/C compressor is on. Thus, who knows what power you do or dont lose, but its true that the compressor itself doesnt take up 15 hp. __________________ 2013 Ford Mustang GT 374rwhp, 360rwtq SAE / GT500 Axle-Backs / Brembo Pack / Track Pack / Recaros / 6spd

06-01-2012, 04:10 PM	#7 (permalink)
'10Anamoly Track Member Join Date: May 2010 Location: GA Posts: 882 Drives: 2010 370Z BS M6 Rep Power: 16	I too would like to be able to set my vent to recirculate without having to run the A/C, which our cars do not allow. __________________ 2013 Ford Mustang GT 374rwhp, 360rwtq SAE / GT500 Axle-Backs / Brembo Pack / Track Pack / Recaros / 6spd

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06-01-2012, 04:02 PM	#6 (permalink)
MattP725 A True Z Fanatic Join Date: May 2011 Location: Toms River, NJ Posts: 1,904 Drives: 2010 40th Rep Power: 16	Also keep in mind that the AC will disengage when you hit WOT. Really step on the gas and feel the vents... the air gets almost instantly warmer for a minute. Otherwise as others suggested take it off auto... I tend to think it is not always engaged because even when heat comes from the vents the AC light never goes off. Also no way you are losing 25 hp...

06-07-2012, 10:21 PM	#14 (permalink)
cossie1600 A True Z Fanatic Join Date: Jun 2009 Location: californee way Posts: 5,380 Drives: 370, Leaf Rep Power: 29