AC Horsepower Loss?

Lovemysi · 07-24-2008, 08:36 PM

Si Drivers,

I've been driving here in AZ with the AC on (as little as possible), but noticed it draws quite a bit of HP out of the engine. The question is, "does anyone know how much HP gets sucked out of the engine by turning on the AC?

Second question is, does anyone know why the window defroster turns on the AC? If so, does it make any difference between that and running the AC?

rickhilbert · 07-24-2008, 08:40 PM

Quote:

Originally Posted by Lovemysi

Si Drivers,

I've been driving here in AZ with the AC on (as little as possible), but noticed it draws quite a bit of HP out of the engine. The question is, "does anyone know how much HP gets sucked out of the engine by turning on the AC?

Second question is, does anyone know why the window defroster turns on the AC? If so, does it make any difference between that and running the AC?

AC draws plenty of power..not sure exactly how much. As for the defroster, the AC helps defrost the windows much faster. This is even more so when it is very humid. There is a way to turn this "auto feature" off...I just cant remember how. Search away!

BigT · 07-24-2008, 08:41 PM

Quote:

Originally Posted by Lovemysi

Si Drivers,

I've been driving here in AZ with the AC on (as little as possible), but noticed it draws quite a bit of HP out of the engine. The question is, "does anyone know how much HP gets sucked out of the engine by turning on the AC?

Second question is, does anyone know why the window defroster turns on the AC? If so, does it make any difference between that and running the AC?

The defroster runs the AC compressor because it dehumidifies the air, which aids in removing fog/frost.

I don't know how much HP the compressor takes, but it would take the same with defrost or regular AC (I think that is what you were asking).

nayilsi · 07-24-2008, 09:38 PM

this guy dyno'd his car with the AC on accidentally.....

If I remember correctly he dyno'd 5-6 whp less

blacklabel7470 · 07-24-2008, 09:46 PM

Quote:

Originally Posted by nayilsi

this guy dyno'd his car with the AC on accidentally.....

If I remember correctly he dyno'd 5-6 whp less

lol mines atleast 25% power lost off full blast.. its redic when im driving turn on my ac and my power goes out the window.. i just suck it up and drive without my ac on because it makes me mad. lol

michinsi · 07-24-2008, 09:49 PM

Quote:

Originally Posted by Lovemysi

Si Drivers,

I've been driving here in AZ with the AC on (as little as possible), but noticed it draws quite a bit of HP out of the engine. The question is, "does anyone know how much HP gets sucked out of the engine by turning on the AC?

Second question is, does anyone know why the window defroster turns on the AC? If so, does it make any difference between that and running the AC?

For your question any load on the engine will make it lose horsepower.
I remember long time ago someone did a dyno on the EP3 (2003~2005 Civic Si) with the A/C off, A/C on, A/C Full Blast. He lost about a total of 15whp with A/C at Full Blast.

volvo9 · 07-25-2008, 09:01 AM

You lose 0 HP when you are WOT, the ac is shut off at that point.

But just cruising around I'd guestimate it to be in the 10 horse range. Someone with a scanguage could figure it out since I think there is a screen telling you how much power your engine is currently producing, but it's probrably an estimate.

Lovemysi · 07-25-2008, 03:47 PM

Interesting. Thanks guys.

Just to make sure, the AC is no different than the defroster then, correct?

volvo9 · 07-25-2008, 03:57 PM

/\ correct

FlatlineSi28 · 07-25-2008, 11:51 PM

wat do u mean the ac is off at WOT

07-24-2008, 08:36 PM	#1 (permalink)
Lovemysi Member Join Date: Jun 2008 Location: Arizona Age: 27 Posts: 79 iTrader: 0 / 0%	AC Horsepower Loss? Si Drivers, I've been driving here in AZ with the AC on (as little as possible), but noticed it draws quite a bit of HP out of the engine. The question is, "does anyone know how much HP gets sucked out of the engine by turning on the AC? Second question is, does anyone know why the window defroster turns on the AC? If so, does it make any difference between that and running the AC?

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Question about AC and Max AC	KraziAzn	Mechanical Problems & Technical Chat	20	06-16-2008 07:19 PM
AC temp reading when max ac is on	FG2z_K	Mechanical Problems & Technical Chat	7	10-11-2007 06:08 PM
AC steal horsepower?	elenamylove	Civic SI	40	10-08-2007 05:34 AM
A/c and Horsepower...	SI SEDAN SHANE	Mechanical Problems & Technical Chat	12	07-03-2007 10:31 AM
How to turn off the AC when the AC is off?	dlux200sx	Mechanical Problems & Technical Chat	3	05-16-2007 04:41 AM

07-24-2008, 09:38 PM	#4 (permalink)
nayilsi Senior Member Join Date: Jul 2007 Location: You mean nothing to me Posts: 9,648 iTrader: 0 / 0%	this guy dyno'd his car with the AC on accidentally..... If I remember correctly he dyno'd 5-6 whp less

07-25-2008, 09:01 AM	#7 (permalink)
volvo9 Senior Member Join Date: Oct 2006 Location: North Attleboro, MA Age: 25 Posts: 2,308 Andrew iTrader: 0 / 0%	You lose 0 HP when you are WOT, the ac is shut off at that point. But just cruising around I'd guestimate it to be in the 10 horse range. Someone with a scanguage could figure it out since I think there is a screen telling you how much power your engine is currently producing, but it's probrably an estimate.

07-25-2008, 03:47 PM	#8 (permalink)
Lovemysi Member Join Date: Jun 2008 Location: Arizona Age: 27 Posts: 79 iTrader: 0 / 0%	Interesting. Thanks guys. Just to make sure, the AC is no different than the defroster then, correct?

07-25-2008, 03:57 PM	#9 (permalink)
volvo9 Senior Member Join Date: Oct 2006 Location: North Attleboro, MA Age: 25 Posts: 2,308 Andrew iTrader: 0 / 0%	/\ correct

07-25-2008, 11:51 PM	#10 (permalink)
FlatlineSi28 Senior Member Join Date: Nov 2007 Location: New Jersey Age: 19 Posts: 269 Matt iTrader: 0 / 0%	wat do u mean the ac is off at WOT