This may be a dumb question - but back in the day I used to drive a Triumph TR7, and when you turned the a/c on, the car would stall if the RPMs were too low.

I have a G37S coupe. I obviously don't have to worry about the a/c killing the engine like that, but how much horsepower does it draw when it's on?


Thanks!

 

The only way to possibly know that would be to do back to back dynos with the A/C on and then off. Nobody has done that so its not known. Minimal.

 

Related in a tangential manner, turning off the A/C during winter driving bumps my MPG by more than 10%(barely 19 to 21+).

 

Never run the compressor if you don't need to. If your A/C light is on, your compressor is running to control the climate/humidity in the cabin. Crack a window, or use the vent if you do not need to defog/ice anything....

Another note: When you go WOT, your compressor will dis-engage. So as long as your foot is to the floor, the compressor will **** off momentarily.

 

The A/C on my cars, in SW Florida, are always on. I know a lot of cars are setup to temporarily disengage the A/C when you fully depress the gas pedal, don't know if that's the case with the G37.

 

It is. Try it on a hot day and you'lll see.

Advice to run with the A/C off is kind of silly for those of us who live in hot and humid climates. I never turn off the compressor. Why would I? The only time that my A/C compressor has been off is when it was on a dyno (once) and when it's been on a track a few times.

I tried measuring the fuel consumption both ways in a controlled test. I drove 220 highway miles to San Antonio with the cruise control set at 71. I drove the exact same route back with the cruise set at the same speed with the A/C off. Difference of .4 MPG. Not worth sweating like a ***** in church for the 9 months out of the year when it's hot and humid here.

 

Agreed. I have see different MPG on trips based upon the winds. Driving to WTX and on the way back might be 5 mpg different just due to prevailing winds. I only turn off my compressor during the winter. Fort Worth is nowhere near as humid a Houston, so the driving force is temperature. The A/C will probably be on almost all the time from March onward.