You can turn off the A/C in auto or manual modes, but it won't let you run it on recirc with the A/C off. You can only run it on fresh air. This is one of my beefs about the G35. Somtimes it would be nice to run the heater on recirc with the A/C off.

It's here!!! '04 G35 Coupe DG/G/5AT/Leather/Premium

 

Does the compressor actually run all the time, or is it just in AC mode, when it's not cooling?


Brilliant Silver/Graphite '04 Sedan/5AT

 

I think that means the ac can come on if the computer thinks it's necessary... I don't think it's on all the time... Anyway I just leave it on auto/econ and if I see some fogging then I put it on defrost ... putting it on defrost definitely turns on the ac

2003.5 5AT Sedan Black/Black Premium/Winter Packages

 

Yes, been that way in cars since the early 70's! Just keep in mind, Air Conditioning can mean heating too, not just cooling!


Brilliant Silver/Graphite '04 Sedan/5AT

 

try this metehod if the defrost with A/C does not work:






'03 Sedan 5a: BS/G, Prem, Aero/Body, Sport, Nav
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Has anyone noticed that you cannot use "recirculate" without the A/C. It forces you to keep the A/C on...never had a car do that before!

-Ted


'03 Sedan 5a: BS/G, Prem, Aero/Body, Sport, Nav
Click for MODS or Vote at Online Showoff

 

I noticed this as well. I think it's by design.

G35 Coupe. Diamond Graphite, Graphite, Premium and wheel and Tire package. Zaino Baby.

 

"You're right - the G35 system always defaults to A/C 'on'. I'm not sure why they did that. It doesn't make much sense. Using the A/C frequently uses more energy and decreases mileage - and it's not really necessary in dry conditions."

I think it has to do with the dehumidification properties of the AC. Or it's to keep the system running to keep the compressor and expansion valves lubed and the refrigerant circulating through the dryer. I'd doubt the compressor runs all the time - it probably only runs when the computer thinks it needs A/C or dehumidification.

As for running the A/C causing lower fuel economy. That's mainly a myth from the olden days where AC compressors were huge and sucked power like crazy (remember the old York compressors that were cast iron and weighed like 30 lbs?). With today's variable displacement compressors and cycling clutches, the impact on fuel economy is negligible. In fact, studies have shown that driving with the windows down uses MORE gas than with the AC on. It's because the windows down kills the aerodynamics of the car, causing it to burn more fuel.

I'd say just let the climate system figure things out on its own...

 

mbryda, it's not that the AC is set by default. You can't even turn the AC off manually, if recirculation is turned on.

G35 Coupe. Diamond Graphite, Graphite, Premium and wheel and Tire package. Zaino Baby.

 

Sure, the AC compressor and system must be more efficient than in the past, but you can't say that it's use is negligible. It's running an extra compressor - it uses energy. Why else would they provide an "econ" setting for the AC?

This is directly from the 2004 G35 manual for ECON: "Economical operation reduces some load to the engine to improve the fuel economy. It allows higher humidity than normal operation."

So...why do we need AC or even Econ AC in the winter when humidity is so low? In my opinion, I don't think it's necessary. I agree that the default settings of the G35 seem odd, but you can get around most of them. It seems only to be necessary when using the "recirculate" setting in the winter where exhaled air increases cabin humidity and causes condensation on the externally cold windows.

 

Again, that's by design and it's a good thing. Here's why:
As we breathe, we put water vapor back into the air from our breath. Also, there is a little bit that gets into the air from perspiration (we just about always perspirate). On a long trip in Recirc mode, you could basically have a greenhouse in the car if it were not for the A/C removing the moisture from the air. You would have large amounts of humidity that would attract all sorts of things - mold, mildew, etc over long periods of time.

In other cars without recirc modes, you get outside air in all modes except MAX AC. The only way to recirculate the inside air is to use MAX AC. This is for that exact reason - they want some outside air to mix in and hopefully lower the humidity.

Also, you get A/C in the following modes on most cars:
MAX A/C
A/C
Bi-level (Air @ face and feet)
Defrost

About the only time you don't get A/C is at vent and feet only. And of course you get fresh air in all modes except MAX A/C.

 

It would be interesting for someone to (in the summer or in somewhere warm) do a fuel economy with the A/C on Econ and the A/C on regular. I'd be curious to see what the differences is/are, if any. I know, for me, in past cars, the fuel economy has not really changed much from summer (I always use AC) to winter, and if anything gets a little worse in winter due to the engine being colder longer.

Heck, I may try it this summer when my car gets here if nobody else wants to.<P ID="edit"><FONT class="small"><EM>Edited by mbryda on 01/18/04 06:36 PM.</EM></FONT></P>

 

I did that. Here in NC the AC is running quite a bit in the summer When I got my car in July, and ever since, I was always disappointed in the city gas mileage I was getting (16.25 mpg, every time). The *first* time I ran a whole tank in a period where I did not have to have the AC on, I got 17.50 MPG. So it definitely makes a difference, and not a negligible difference.

2003.5S AT / DP / Graphite / Premium / Aero / Sport / Splash

 

I am also in NC. I basically seem to get about 20 - 21 mpg in the city, summer or winter. I don't use the AC in the winter except when the defroster is on, which isn't much. My gas mileage always seems to stay pretty constant, no matter if I use the AC or not.