I leave the system in "Auto" all the time. In hot weather when interior temp is quite high, the system closes the Recirc door, but does not use maximum fan speed. Have I missed something in the OM? I know it can be manually set to "Max", but what is the point of "Auto"? Also, the Recirc door stays closed for a long time, probably due to the lower fan speed. Any thoughts welcome. Thanks.

 

Are you leaving it in FULL AUTO meaning it says auto up top ?? I often put it in auto then immediately hit the recirc cuz I hate georgia air. But it still modulates fan speed all the time, can easily hear it when going under shady areas.

I assume you say it's not going into full fan speed cuz when it's in auto, you can hit the fan all the way up and it's obviously louder/faster right ?? hmmmmmm

I guess I've never noticed, I know when I got in the car today it cranked up the fan rather high, but I guess I wouldn't have known if it was full or not, maybe I'll test, not likes its 98 with a "feels like" of 109 today .. ick.. with no central air, damn house.. (we have air, it's just broken right now)

 

Yes, says "Auto" & recic light goes on; pressing fan^ increases speed, so it's not maxed. Will have dealer check when I bring it in, though no "real" issues to report.

 

Mine did that for a long time, until it got rerally hot here in Florida. I got mine in February, so I gradually got used to what the A/C does.

For along time, it would blow a little higher than normal. If I pushed the fan button once, I saw about 4 bars on the display, meaning it was blowing about 3 bars. Now, when I start the car in the morning, in the garage, it does the same thing, but when it has been out in the sun for a while, especially during the hotter part of the day, it will wait about a minute for the A/C to begin cooling, and then it will blow on High speed, so it may be that it has to be a certain temperature in the car before that will happen.

I have found it to work quite well now that I am used to it. My 96TL always put the fan on high no matter what the temperature in the car was, as long as it was reasonably hot, which made it noisy and sometimes uncomfortable with all that air blowing, so this seems to be a little more geared to quiet and comfort, but you do have to manually raise the fan speed sometimes, so it isn't perfect.

 

I belive that there is a program for this, in steps. Because the highest fan speed is noisy, the system tries to cool the car faster by recirculating the air first, before resorting to higher fan speed.

Also - instead of raising the fan speed, why not just lower the desired temperature?

 

Yes, that is what I meant about the fan being noisy and the system being geared for quiet and comfort, but I don't think lowering the temperature will result in any change, unless you put it on the lowest temperature (60) which will put it in max mode and it will go balls out to cool, but anything above the lowest temperature setting will not change the program, but will only result in the A/C working longer to achieve the lower setting you dialed in.

The same principle works in your home air conditioning, where setting the temperature lower does not result in the house getting cool faster because the temperature setting has nothing to do with the output of the air conditioning unit. My wife used to think like that but I think she has finally come around to my line of reasoning.

 

Yeah, that's a woman thing. Especially in cars. They all think setting the temp lower will make it cool faster.

I have a theory on why the fan speed may not reach high (just a theory, I have no idea if I am correct). Could it be that if they move too much air through the system too quickly, it won't have time to get as cold? If you think about it, the amount of time the air spends within the cooling "loop" (I don't know the terminology), the colder it will get. There is probably some kind of tradeoff here. What do ya'll think of this theory?

 

jjs: "dwell time" certainly has an effect. If you think of the air passing thru the heat exchanger, it has to come into contact with the fins in the heat exchanger to go from warmer to cooler. The less time the air is by the fins, the less temperature changes hands.

I don't know that it would really effect the system in the car, but yes, it's a definately sound theory.

Computer cases and heatsinks are very suseptible to that problem.. People think just throw more fans at it.. and the air goes rushing thru, not spending enough time in the heatsinks to pull the heat out well..

(ok that and I live with a friend who has a masters in aero and thermo dynamics, he taught me about dwell time and heat transfer and stuff) So I applied it to one of my pc cases I was having troubles cooling, and gee, it worked..

It might also not crank it up to full, versus the 96Tl as maybe we have bigger ducts and maybe a bigger fan motor/output rating (just throwing out guesses). We also have the 2 vents in the rear seat, so it's not trying to throw the air from the front all the way to the back.

In either case, I just leave it all on auto except forced recirc, it speeds up to cool, then comes down to nearly silent once it's done. I generally keep the car between 73 and 77. It will drop to 60 if it has to on a really hot day, and then come back to it's normal set temp.

What I hate is the people who get in and crank it down to 60 on a hot day. Those are the people not used to automatic climate control. "JUST LEAVE IT ALONE".. it will go to max, then come back to what it should. eesh.

 

I concur with Sherlock. Once in a great while the temp exceeds 75 here in the Northwest. Auto Mode works very nicely - even without touching the recirc. Much nicer and certainly more effective than my '03 G35.

And ya know what's best .... no one's bitched or moaned (so far) about rattles from the fan or the clicking sound of the switches!

 

Ok,

I'm reading this series of threads and now have a question.

Is the recirc light supposed to come on when the AUTO button is pushed?

On mine, the recirc light doesn't come on and if I push it, the AUTO setting is turned off.

Just curious....

 

The recirculation light will come on when the conditions require it. Usually, it will come on when the car is very hot and the system wants to cool the car down as quickly as possible, so it goes into recirculate mode. This means it doesn't draw in any hot air from outside, but uses the air already cooled. When the inside temperature reaches a programmed level, the recirculate light will go out and it will again draw in outside air.

 

and to add to ron A's correct answer, if you push the Recirc to turn it on, yes Auto goes out to indicate that it's not in 100% full auto. it will still moderate fan speed and the zone temps if you have navi. It will also moderate between dash/bi-level/floor if it needs to. You can selectively force any of the "auto" options and it will still auto the rest of them.

If you've ever had the occasion to travel from a very cold place to a warm place in the same trip, you'll notice that the a/c comes out of the upper vents and the heat comes out of the floor vents. And in the course of a trip I've had it go from a/c blowing at me, and very subtley migrate to the floor as it applied heat, was kinda neat.

 

Thanks gentlemen for the replies. It clears things up for me!

 

Thanks, everyone. I've been away from the forum for a few days and couldn't respond. My previous cars w/Auto climate maxed the fan speed at startup on hot days, and this is the behavior to which I was accustomed. Maybe just a Euro thing.