answered question

answers (3)

jp95zm6
1
Vote
BEST ANSWER  chosen by asker   |  jp95zm6  |  February 21, 2009 06:37 PM
Horsepower is not reduced, but you 'spend' some of it running the compressor. 5 to 7 horsepower would not be uncommon. Lowering the blower will reduce the load on the compressor, since less air moving through the system results in less heat transferred to the a/c system. Raising the temperature setting typically will not reduce the a/c load, though. It just reheats the air after the a/c chills it. Running recirculation mode or 'Max' is the most effective way to reduce the load from the system, and thus maximize fuel economy with a/c on, especially for longer trips when the cabin has a chance to cool off.
source(s):
Thermal Systems design experience.
Asker's rating:  

Comment
pvera
pvera  |  February 21, 2009 07:14 PM
Another thing we did not mention is the size of the engine. A 300 HP V-8 engine with a 7HP penalty due to AC won't feel it at all. The same 7HP drain on a 120HP 4-cylinder car will make it feel sluggish.
pvera
2
Votes
pvera  |  February 21, 2009 04:40 PM
If it runs off a belt that feeds from the engine power, yes, it is considered parasitic, so it lowers the available power that can be used to move the car.
Comment
cee-jay
1
Vote
cee-jay  |  February 21, 2009 06:24 PM
My suggestion, is really just use the AC if you need it. You do get a better agility without it on.
source(s):
my daddy's a mechanic
Comment
pvera
pvera  |  February 21, 2009 06:29 PM
I agree, if you are going to be putting a heavier than normal load on the engine you should switch to just the fan. Also, if you are going to be driving at a steady speed, say an interstate, then you can probably use just the fan and the car won't get too hot.
140

ask any question

Top of Page
Buy Mahalo Dollars
WITH CREDIT CARD OR PAYPAL

Please log in to use this function.