Defroster on- AC Compressor on?

RememberThisTitan · 09-26-2004, 02:20 PM

Now I know that almost all cars today have the compressor on when you put the defroster on. Now if you push the AC button to turn the light off, will the compressor turn off? I ask because I would think the compressor being on hurts gas mileage. Anybody know?

jburson250 · 09-26-2004, 03:20 PM

Yep, the compressor stays on 'til you turn the ignition off. The real (and unanswered) question: is this a feature or a bug? BTW there's been other threads over the past months on this phenomenon.

Blizzard · 10-06-2004, 02:03 PM

Sorry to revive this old thread again, but I don't remember ever seeing this posted in any of the different answers. I was looking through the owner's manual the other day trying to find out why the air flow control knob had detente positions between the pictures.

Anyway, the owner's manual says that the only way to shut the compressor off after running the defroster for more than one minute is to shut off the truck OR turn the fan control dial to OFF. I tried it this morning and it worked. Of course, it also says the AC lite is not supposed to come on with the defroster, but mine does every now and then. So your mileage may vary....

jburson250 · 10-06-2004, 05:00 PM

And when you turned the fan back on, what happened? Did the compressor stay off, or come back on?
I've been fiddling with mine, convinced there must be a combination of fan knob and distribution knob positions that will allow the compressor to shut off and stay off (as long as you aren't selected to a defrost position). I should have read by owners manual as carefully as you did. I'll give your method a try.
As far as the extra detents, selecting one does slightly change air flow. My wife's Passat flow controls are similar. I haven't taken a car or truck HVAC system apart in about 12 years. From what I remember the distribution knob changes the position of "dampers" (via vacuum "motors" inside or outside of a central plenum). The air ducts to various outlets are connected to sections of the distribution plenum. It's probably more sophisticated than I'm describing, but the intermediate detents allow you to customize to (some degree) where air is flowing to.

TitanicSE · 10-06-2004, 08:35 PM

Simply tapping the A/C button in my wifes 04 Quest will also shut off the compressor after using the defrost mode. See if that works on the Titan as well.

aznsupra · 10-06-2004, 08:41 PM

Quote:

Originally Posted by TitanicSE

Simply tapping the A/C button in my wifes 04 Quest will also shut off the compressor after using the defrost mode. See if that works on the Titan as well.

it doesnt, thats the thing, when you turn on the defroster, the ac compressor will stay on NO MATTER WHAT even if you turn the ac on or off,and if you turn the fan off yes it shuts off, but then u turn the fan back on and the ac comes back on AGAIN despite the ac button being off. Unless you turn the ignition off, your compressor is on for the duration of the trip.

titanwild · 10-06-2004, 08:45 PM

Quote:

Originally Posted by aznsupra

it doesnt, thats the thing, when you turn on the defroster, the ac compressor will stay on NO MATTER WHAT even if you turn the ac on or off,and if you turn the fan off yes it shuts off, but then u turn the fan back on and the ac comes back on AGAIN despite the ac button being off. Unless you turn the ignition off, your compressor is on for the duration of the trip.

Supra is absolutely correct. It's not right, but that's how it operates!

gedunk · 10-06-2004, 08:47 PM

I experienced this yesterday as well. Had the defrost on along with the A/C compressor light being lit. Turned to regular A/C position and pushed the A/C compressor button to make the light go off. The compressor continued to run. Then turned the fan speed to "0". This did shut off the compressor. However, when turning the fan back on, the compressor still came on regardless of it being lit or not. The only thing that fixed it was killing the engine and re-starting. Very odd.

TitanicSE · 10-06-2004, 08:55 PM

That sucks. I've read in Frontier forums that the new (03-04) Frontiers do the same thing! The ONLY thing I can come up with is maybe it somehow cuts down on that mildew smell you sometimes get after shutting the A/C off. lol....hopefully Nissan has a reason!

*Titan Critter* · 10-06-2004, 09:19 PM

the reason listed in the manual is to keep the humidity out of the air. not a real strong justification, but that's all it says.

SupraTitan · 10-07-2004, 09:25 AM

Noticed the same thing and find it very annoying. Since there is a button to turn the AC off, you would figure it would turn off. Also nissan's reason is bunk, usaully when I turn the ac off I roll down a window so I could care less about hummidity coming in the vents. This is going to be much more of a pain this winter, I don't want to drive around all winter with the ac on, plus the air is so damn dry the last thing my sinuses want is even drier air coming in.

*Squid* · 10-07-2004, 02:01 PM

On my XE the only time the AC compressor is on when defrost is selected is when the temp select is in the Blue.If I place the temp select in the red the compressor goes off and the air goes from cold to hot.
This makes sense to me in the summer I want to dehumidify but not roast and in the winter I want to defrost/defog and not freeze.

TitanicSE · 10-08-2004, 04:33 PM

Ok all...not sure why it's being said otherwise but......lol..here goes..

I just picked up my 04 SE CC and the HVAC system works EXACTLY the way our 04 Quest SE does! meaning....if you turn the dial to DEFROST, the A/C compressor kicks on. It will stay on EVEN if you switch to the dash vents etc. HOWEVER, and this is why I mentioned it about the QUEST in a previous post, once the compressor is kicked on by turning it to DEFROST, and you switch to say.....top vents, the A/C compressor WILL turn off if you hit the A/C button....without having to shut the engine off and restart it! I did this MANY times sitting in the driveway to varify it so....it does work like the new Quest system! Try it.

gedunk · 10-08-2004, 06:51 PM

Sounds as though yours works as it should. HOWEVER, there are those of us in which it does not. When switching to other modes after having it on defrost, the compressor STAYS ON even though the light goes off when pushing the A/C button. Other than turning the fan speed to "0", nothing turns off the compressor except for killing the engine. Personally, it's a pain in the rear for me.

TitanicSE · 10-08-2004, 11:19 PM

Makes no sense though. There HAS to be others here whos' HVAC system works like mine does! They can't ALL be bad...yet mine is ok.....can they?