RayL

Can anyone explain the logic behind the 6th gen heating/ac system. Worked great for me this Summer but on these colder days it seems illogical to me to have the AC on all the time? What's the thought process/functionality behind this?

robmandude

yeah....I had the same question... first cold wave ame thru TX..and heater is on , But A/C stays on....

Tek-Niq

iTrader: (3)

press the button again until it says a/c off in the screen. you don't wanna run a/c with the heat it don't blow hot like it should.

I just bought a 2004 haven't changed my sig yet..................

DeusExMaxima

iTrader: (1)

I think the idea behind it is to blow dry AC air. I notice that the air is more comfortable when AC and heat are on. Just a guess. Besides, my new 05's climate control is F***cked up and needs to be fixed. Lets see how NIssan service is.

2004 Smoke

I think this is pretty common now (to have a/c on even in winter). Our Civic won't let you turn off the a/c when defrosting - the manual says it works better.

lightonthehill

The dehydrating process is as important as the cooling process in a properly functioning AC, whether in car or home. This means air conditioned air is far better than normal (more humid) air in clearing moisture from the inside of windows.

This is now the normal way defoggers work on most cars. My only complaint with the 6th gen Maxima is that turning off the defoggers (or even turning off the AC/H system entirely) does not disengage the air compressor. Turning off the ignition will do so, but I would prefer being able to turn it off while continuing to drive.

Granted, the manufacturers now design AC/H systems with the idea they will almost always be on, and have made them so efficient they have very little effect on fuel economy. But I am 'old-school', and I like to be able to simply turn things off when I'm not using them.

Yama1yzf

There is an A/C button on the heating controls. Just push it to off and the compressor turns off. I don't like the default being A/C on either but it's easy to turn off if you want to.

jc53

Yes, but it's a real pain in the caboose when you have it on defrost and it's cold out, because the second you turn off the A/C the window fogs over again. So you are left with a choice...defrost the windshield and be cold, or be comfortable and lose visibility! Doesn't make sense to me.

CanadianMoFo

A/C doesn't just put out cold air. It stands for two words. Air and Conditioning. You are conditoning the air to whatever property you want. It could be cold, hot, dry, or humid. All depending on the function of the equipment that you are using to condition the air.

Try this, turn your heating control all the way up, leave the A/C and defrost on and see what happens. I'll bet you that you get warm dry air out of the vents. That's exactly what its designed to do. Its taken cold air in, heated it up, and removed the moisture. The air has been conditioned.

And viola...your windsheild is clear and the interior of the car is warm.

MaxMus

huh? have you actually tried the system yet? I set mine between 74 and 78 degrees and it's perfectly warm to me.

jc53

thanks for the explanations, maxmus and canadienmofo. I'll crank up the heat a bit more and see what happens. I guess I'll just have to stop "stereotyping" the words "air conditioning".

Souljourner

The "AC" button just turns off the availability of the AC system. When the button isn't off, that doesn't mean the AC is actively working. For example, when you're just using the heat to heat the cabin, the AC won't be used regardless of the position of the button. If you switch to defrost the windshield, the AC will be used, because the act of compressing the air in the AC system removes humidity, and thus the air is dryer, which makes the defrost system work much more effectively (on interior fog). Please note that after the air goes through the AC system, it then goes through the heating system, and comes out just as warm as non-AC'd air.

-Nate

kapesports

this very true...... good work CanadianMOFo..

Now, will this harm the compressor ? what the impact if we live it on everytime we need AC/ heat ?

Mystery

Yes thats very true. In most cases i have found that 80 degrees with ac on clears my windows very nicely. The only time i ever really have problems are in the rain and some times when there is a nice coat on the car after being off for a whille.

It took me a while to figure out the best combo.

CanadianMoFo

That has already been discussed in a different thread. Once the compressor is turned on it will not turn completely off. The way I understand it is, even if you press the A/C button to shut down the compressor it still idles even though its not really functioning to dehumidify the air. It saves wear and tear on the compressor.

Basically if you're hoping to save 1-2% on fuel use you can't turn on the A/C or defrost once you've started the car. The only way for the compressor to shut down once you have is to turn the car off and restart. Someone said it is covered in the manual. But reading that thing is always the last resort.

CM.

jaydabee

Back in the day (alright, late 70's) it was pretty much common knowledge that the ac compressor was used to provide dry air for the defroster. Seems like a lot of people grew up not knowing this and are now shocked when they see a little light on there dash coming on that ACTUALLY TELLS THEM WHAT IS HAPPENING.

I just leave it the way Nissan intended it to be used and my milage is right at 24 mpg.

maLniveK

I like the old way better when you be able to have defogger and heater on to my face at the same time. This heating system doesn't have that way. And also I would love to have A/C circling inside my car not from the outside. I think they need to redesign the cooling/heating system.