WTF does Max A/C do?
 

I've heard people say that the only thing Max A/C does is simply operate the flap which shuts off outside air, so that air inside the car gets cold faster. But if that's all it does, then why does the fan speed increase as well?

Might be an aux fan that guides the recirc air to the inlet

Hmm......I thought there was only one fan (usually on the firewall near the wiper motor)

I always thought it was because of different pressure in the car once the air is being recirculated making the fan blades go faster.

:idk: None of my cars have that. Auto climate control FTW.

Several cars, like the Ford Fusion, have both automatic climate control and a max A/C setting.

It may not be labled "MAX A/C" but if there's a button that recirculates the air you're doing the same thing.

My guess, and it may be what Particle man meant as well, is when the A/C is set to get fresh air it is putting new air in the car. The old air has to be forced out somewhere creating higher pressure in the cabin. The fan runs slower because it has to overcome that pressure differential to get the new air in the cabin. When set on recirc it is drawing air from the cabin, cooling it, then replacing it back in the cabin. The fan does not have to work against the increased cabin pressure, its job is easier, and as a result it can run faster. I know in my truck when the A/C is set to get outside air its output increases if I crack the window open.

you said it a helluva lot better than I did :lol:

it turns the recirc on.

Hmm, makes sense. All cars have a cabin air exhuast, usually somewhere near the rear fender, but it's covered by a rubber flap so some amount of force is necessary to push air through it.

So then if all Max does is make the air recirc, then why do so many cars have both a Max button AND a recirc button? Do they think people are too stupid to understand what recirc will accomplish?

They have both so you can use the recirculate function even while not using the A/C. Comes in handy near skunks and scumbags.

Rider, yours does too. It's the re-circ buton.

With the benefit of time a shit sandwich can be made to sound good.:lol: I think I got where you were coming from.

Homeslice, yes, people are too stupid to understand what recirc will accomplish. The "too stupid" factor dictates far too much of car design today.

What? People don't understand if you recirc cold air thru the a/c process again it gets colder?

That is one of the more interesting things I have read recently... and since I have time...

Shit Sandwich
On whole wheat, rye, or a seasame seed bun... Mr Hanky's sandwich spread cannot be beat... The creamy texture combined with nutty chunks and a hint of whole corn kernals make this a great treat for any occassion. Move over JIFF, this ain't yo' momma's peanut butter... this is a special gift from the gods of taste! Savor the thick aroma... it's the kind of food you can smell from miles away. Lick your lips... the smell alone has your mouth watering... Now dig in... it's ok if you like th spoon, we don't mind.

It does more than recirculate the air (most systems have a separate control for that). Max A/C also runs the compressor and auxiliary engine cooling fan at a 100% duty cycle. Normal A/C runs both intermittently, you can probably hear/feel it when the A/C compressor clutch cycles, particularly if you're sitting idle.

Called out on my hyperbole and proven wrong (very wrong).:lol: Nice work.

:lol:

Why wouldnt you want it to blow harder? When I say harder I really mean BJ.


I always turn on the re-circ button. Why cool hot ass air from the outside. Bitches, get your own damn a/c.

When your car has been sitting in the hot sun for awhile, the inside temp is hotter than the outside temp........So IMO, it's better to let it suck in fresh air for a few minutes before hitting the recirc button.

that's why most car manuals recommend running the A/C on MAX and driving for a little bit with the windows cracked so the A/C can force the hot air out.

Hmm, I'll have to check that out, thanks

If the windows are cracked, it defeats the purpose of running Max's recirc feature :p

Run it on normal while the windows are cracked, and then switch to Max when you close the windows.

So then you're not only trying to push the hot air out you're trying to cool the hot air from outside at the same time? You do what works for you and I'll do what has always worked for me :lol:

Dude......My point was, on a hot day the air inside is going to be hotter than the air outside. So why not force as much of it out as possible, before activating recirc?

crack 'em open and go 60 down the highway and let the air get sucked out and pushed out by the recirculating AC ;)

Or take the bike.

I lqeave my windows cracked open during the day.

You guys will debate anything won't u.

No we won't!














:lol:

:lol

I don't have A/C. I use natures a/c thats usually not that cold during this time and can be filled with dirt. Mmmmm.......breath in that fresh nature a/c boys.

I hate to do it to you in a non-fashion related thread, but I think 'slice has the right idea here. :lol:

You actually make your A/C less efficient by using recirculate with the windows down because air is being drawn out of the cabin; the same air your A/C is trying to draw in. You'll get more air flowing through the system with your window down if you let it use the outside air (which, in that scenario, is also cooler to begin with).

Try driving with a window open and hit the recirculate button on your A/C. At the same fan speed, there will be considerably less air coming out of the vents than you have in non-recirculate mode.

I must've read this 10x and I still can't figure out what you're trying to say.

Tell that to the dudes writing the instruction manuals then. :shrug:

I believe he's saying he just rolls down a window. The air is full of dirt, and it's hot outside in his local at this time of year.

I thought he was saying he farts a lot :scratch:

If I ever see a manual written that way, I will. You actually made me crack open the owners manual for my truck, but all it says is to use recirculate for quick cooling or in dusty/high exhaust fume areas. It makes no mention of using recirculate with the windows down. :shrug:

The manuals for my Grand Prix, Achieva, Explorer, and Mountaineer (not sure about the Kia or the Subaru I'll have to check) all said crack the window slightly for the first few minutes of operation to allow the MAX A/C to push the hot air out and then close the windows to allow the system to dehumidify the air and recirculate. It doesn't say "windows down" (nor did I say that).

I don't know if it's right or not (and I honestly don't care :lol:)

I know this is an old ass thread but...

I've service/repaired a lot of AC systems and I've never seen one like this. Running the compressor 100% will just flood/freeze up the Evaporator.

Yes, that is because he doesn't know wtf he is talking about. redflip

Max A/C is for cabin air recirculation only. Notice when you have a Recirc button, you don't have a Max A/C setting. When you have a Max A/C setting, you don't have a recirc button.

Most compressors nowadays don't cycle anyway. They are either ON or OFF. The pressure control is done with valving in the compressor itself. This is not to say that the engine controller cannot turn OFF the compressore if the high side pressure becomes too high or too low or if you in a W.O.T. scenario.

My Kia has both a max and a recirc setting. I can recircate the air on every setting. When "Max" is selected, I can't override the recirculate feature.

The Subaru only has the recirc button and no "Max" setting.

If your objective is to "push" hot air out the window, you'd be better served by using the Normal setting, since it pressurizes the cabin because it's drawing in outside air. On the Max setting your cabin air isn't pressurized, therefore you're not pushing as much air out the window as you could with Normal.

Same with our work '04 F-150. The only thing is max a/c just blows through the top vents. I always have it set to top/bottom and hit the recurculate button.

"my" objective isn't shit. I said that's what the manual said, not what I believe.

You are wasting energy trying to convince me of something when no such action is needed. Your energy is better spend making fun of people who call the fire department when they lock themselves out of their houses or people who drive sports cars with automatic transmissions.

Kthxbye

I have both MAX and re-circ on my 1-Series. Actually, I have MAX and three settings to recirculate air. If I select MAX it drops the selected temp to 60 and does a full lockout to recirculate the air. The MAX selection also locks out the passenger's ability to select their own temp. I'm still trying to figure out the three settings on re-circulation. I might have to RTFM :lol:

I couldn't have come up with a better rebuttal. Thanks for talking out your ass and saving me the time. redflip

Dude I'm a service engineer for a car company...and have worked with car companies since I was 22. If I know anything in this world...it's cars. redflip You guys just guess at shit...or try to analize things using general common sense. Your original statement that the compressor cycles because of "Max A/C" or "Normal" just is not true.

Those that have Max AC and a Recirc button is simply for air venting direction (Max AC) and then % outside air using the Recirc button.

The inside cabin is in no way "air tight" in any vehicle and you are always drawing in at least 10% outside air on the recirc button.

If you want to cool the cabin quickest and it's hot outside, you use the recirc function. This will make the differential temperature across the evaporator the lowest.

Again, what if the interior temp is hotter than the outside temp?

And it probably is initially...but put in on Recirc. and 10 seconds later the temp will be less then the outside air temp.

10 seconds? Doubt it. I don't drive big old American cars with awesome AC, so it takes awhile for my AC to get cold. I would rather use the Normal setting for the first 30-60 seconds so it can force hot air out, before swtiching to Max.

I thought Max engaged the secret R12 subsystem for that extra bit of cooling that R134a alone just can't give.

So two decades in the industry and you think GM builds a quality product and think cars have either a Max AC button OR recirculate. And I'm the one that doesn't know what he's talking about. :lol

All cars I've driven have both. All cars I own kick on the auxiliary cooling fan as soon as Max AC is selected. Observation skills bordering on retarded should still allow you to at least gather that if cars have been your life for 22 years. If I was wrong about the compressor, so be it, I'm not opposed to learning from someone here. Provided they at least come across as knowledgeable, beyond just claiming to be while regularly showing otherwise. redflip

Or you could do what everybody else does and roll the windows down until it gets cool?:idk:

It doesn't matter that is SAYS MAX AC, what matters is what it does. FWIW, my 2011 Mazda 3 has both, but the MAX A/C does nothing but ensures that the Hot/Cold is all the way to the full Cold. The condensor fan runs whenever the A/C is turned on regardless if it is all the way to the Max AC position. The Recirc button does just like it says. Recirculates. Why they even put "Max A/C" I can only guess is so the clueless don't leave it still in the "blue", but not all the way in the full blue range. Ford, GM and Chrysler always used only Max AC, which forced recirculation.

Well, apparently you have not driven a GM, VW or Mazda because they don't. The A/C fan on all GM vehicles was always a function of the A/C relay ON and A/C high side pressure. I would be that Max A/C does not even have a signal to the body controller. My Mazda 3 runs the A/C fan when the A/C is on and the A/C high side pressure is above a certain threshold. Max AC is not any type of input.

So now the question remains....do you have BOTH a recirc. button AND a MAX A/C button? Or do you have a Recirc button and lettering that says Max A/C because then Max AC doesn't do anything.

I should have said that Max AC acts as a recirc function if you don't have a button. If they put both there, the MAX AC is only to make sure you put it to full cold.

:?: no such car

I meant Mazda 3. I don't why I added MX the first time I mentioned it..so I'll change it.

Careful! He will attempt to "convert" you now!
:eek:

bzzzzzzzzt- sorry, but thanks for playing. Tell him about his fabulous door prize, Al!

(just selected "MAX A/C" and turned the Temp into the red zone and, woe and behold, hot air came out)

Not trying to bust your balls (okay, maybe a LITTLE) but not all cars function the same way. ;)

Wow, you guys put a lot of thought into this whole windows-up windows-down thing. :lol:

I wondered the same thing about Max A/C when I was a kid. Our AMC Hornet (yeah, baby) had a label on the knob that said "Max A/C - Desert Only" or somesuch. I spent many a family vacation (of the non-desert variety) wondering from the back seat what would happen if we turned it on.

I was pretty disappointed when I got older and realized it was just a recirc control. :lol:

I'm not sure why you think I'm trying to force you to do what I do (which would be impossible anyway). But if someone says something I don't agree with, I'll speak up, and I'll keep doing it again and again. I don't hold back just to try and stay "buds" with someone.

An internet debate, son. Try to keep up.

I could say the same to you, friend.

Little disappointed it wasn't an MX3. Lil 1.8 V6 was entertaining back in the day.

What happened to the Golf? And the Geo or whatever it was? Dude you must change cars like every 6 months.

Desert Only? LMAO....

Of course this is AMC we're talking about. A company that comes up with crap like the Pacer and the Gremlin can't be very smart.

Are you just acting stupid? You just turned the heater control knob to full hot. No shit it is gonna blow hotter when you turn it all the way hot. But do you need a label that says "Max AC" to tell you that putting it all the way cold puts the door vents fully to the evaporator? Is it not obvious? The answer is NO. My point is the label Max AC does nothing IF you have a recirc button.

Would you like a Max Hot label too?:idk:

It was a lease.....I sold it to CarMax (yeah I knowredflip) and they gave me 1900 bucks more than I owed on it after 15 months of driving it. I put 995 out of pocket on it and it was 200 a month lease.

This Mazda was 999 down and 199 a month. So...I sold the Golf, put the 995 down, kept the same payment and bought 3 sets of race tires with the 900. redflip

I sell cars when it's profitable. :idk: You just have to know when to sell and be forceful at what cost the cost vehicle needs to be.

OK......just sounds like a lot of money for the priveledge of always having new cars........You spent 200 x 15 = 3,000 plus the 995 out of pocket. Yeah you got 900 profit from selling it, but you still spent over 3,000 for 15 months of driving....

Seems like you could have bought a 2 year old used Golf, which would have only depreciated 1-2K over that same amount of time, if you negotiated right.

Cuz I like telling people what to do redflip

Shoulda kept the Golf anyway.....Mazda 3 seats have no lumbar support last I remember redflip

Still wrong. If I have my A/C running in my truck (Nissan), car (Mazda), or SUV (BMW) with Recirculate ON, then switch to MAX, you can HEAR the changes to the air speed. Exactly what that change is, I don't know, but it's clearly doing something more than recirculating.

And the Nissan will modulate the auxiliary cooling fan when normal AC is on, whether or not recirculate is active. It runs 100% of the time MAX AC is selected. Whether it's the same on the others, I don't know, my wife drives them more than me.

So, clearly not all AC systems are created equal. The only thing more clear is this subject has run its course several times over. Should you feel the need to "debate" this further, please PM ParticleMan. :)

But if the A/C is set at MAX on a treadmill, will it take off?

Dude, stop that. The universe will implode :lol

At least it didn't have a douchebag auto transmission in it. :lol: Three on the tree, baby.

Appropriately, my dad gave that car away to our garbage man.

A manual tranny on the steering column? Typical American thinking.....Too afraid to put the stick on the floor, for fear of losing that vaunted 6-passenger claim in their advertising.

We had a truck with the manual tranny on the column. It was pretty neat

Three on the tree is a pain in the knee. I remember the saying, just never remember it being a problem.

Almost an additional 40 posts since I revived this...Nice.

It's forcing the air out of only the center vents...but you could have just PUT it on the center vents. :idk:

Remove your HVAC control head and then turn the thing ON to Max AC. If there is a different signal being sent in Max AC, then I'll agree that there must then be varying high side pressure ranges to run the condensor fan.

Even going from center vents to max, the sound changes and the air comes out faster

I would be taking it out of gear everytime rain hit the window.

:lol never thought of that. The wipers were on the left side of the dash. Two speeds, on slow or on fast. And off. :)

That is only 14 months since the first month comes out of the down payment. redflip


Two hundred bucks a month for a car you have to do nothing to until you get rid of it is pretty cheap. You do this over 5 years and you're paying 12k, but getting a new car every 1.5 years. You actually make out better unless you keep the vehicle for at least a few years after it's paid off, but who wants a car for 7 years.

Since these hold there value well, how much do you think I could have bought a 1-2 year old used one for? Then sold it for after 1.5 years? More than 2k?

Yes if you DON'T have a recirc button. If recirc is off...then ...um no. redflip This is saying the center vents are ON.

Wrong again. Maybe after 30 years in your field you'll grasp the basics.

Wrong about what? You really have no backing to even respond.

You either recirculate the air OR you recirculate the air and force the air all through the center vents. Do you think this noise is coming from somewhere else? Like ur ass maybe?redflip

When I use the recirc button and have it set to the center vents it still isn't the same sound or force as Max A/C. Again, I have both a recirc button and Max setting.

Wrong in your response to PM, whose post was an accurate description of how the AC works in all our cars.

A quick walk down to any car in my garage would disprove every post you, a self-proclaimed expert, have made in this thread. That's all the backing I need.

Well. most don't, though I'm guessing that there is 5-10% airflow going to the other vents even when in the center and then 100% to the center on Max AC. Put it on the center vents, then on Recirc and at max blower speed. Then, see if there is any air coming out the floor or defrost. Then do this on Max AC. Compare the results. They may be only putting air through select center vents as well. The mode selector doors have multiple airpath channels, so this is most likely what is going on. It is just diverting airflow in a different manner.

What car is this? I'll test it.

He never explained how ac works in this entire thread. Read again.

No thanks, I'm good. His description is accurate to everything I own. Yours have not been.

:lol

He is mentioning ventalation..not AC. Do I need to describe the difference?

No, he's saying there's an audible difference between running normal AC, recirculate on, with air directed out the vents vs. Max AC.

You're saying there is no difference.

I beg you, please do not try to explain anything further.

You're not getting the last word. :lol:

OK...so he notices the air is directed differently changing the sound. BFD. Still doesn't change the fact that Max AC doesn't do anything in regards to the AC system running under the hood.

Coming up on 100 posts :rockwoot:

So you've gone from "you either have Recirculate or MAX" to "MAX doesn't do anything but turn recirculate on and make it full cold" to "ok, you can have both and maybe it directs the air differently, but it doesn't change anything in the system!" And it would take me all of 3 seconds to still disprove you using my truck as an example. :lol:

I dub this the last word. :lol

Ok now ur just upping ur post count punk.:yum:

Hans, do you know what Max AC does now?:lol

Damn West coasters and their late night final words!

I know what it does in my truck. Have you figured out what it does in a GM yet? :lol: