ASH8

By Benzene (Benzine).....

This is something brought to my attention on net and while not directly attributed to Mazda but all car manufacturers, I do recall many years ago a guy in the US trying to sue MNAO after he purchased a new Mazda 3 and why his young family (I think wife and or kids) are falling sick, he had interior independently lab tested and was alarmed at the chemical vapours/residue present....particularly when car is left outside in sun...(his story is on YouTube)

Anyway, Today I came across another alert from 'a' blog....here is copy of the alert....not mine....

(**) My view was about 'WHY Car Manual' says to expel Hot air out of car before one turns on AC was to reduce AC load (Compressor) on Engine, in other-words your AC won't have to work as hard to reduce cars interior glass-house temps.

Remember AC's should normally only be operated on ''recirculated air'', not with ''fresh'' air entering cabin

However, the writers warning does make one think...

Bladecutter

Snopes doesn't agree with you:

snopes.com: Benzene in Automobiles

BC.

sd1611

Don't believe everything you see on the internet.

snopes.com: Benzene in Automobiles



Oops, I guess you beat me to it.

Dr. ZoomZoom

iTrader: (1)

Benzene is some really nasty stuff. It is an aromatic six-membered ring that is entirely sp2 hybridized, which means basically that it is very flat. Because of this characteristic it can "slide" in between major grooves in DNA, disrupting H bonds. It is a fantastic solvent given its higher boiling point, and ability to solubilize compounds; I have litres of benzene and deuterated benzene in my lab.

Having said that, I think the total amount of benzene in a car day after day being that high is false. When solids are formed, especially in a rapid manner as the polymerization that leads to plastic, the solvent is trapped inside. Over time these solvent molecules do escape, but that rate provided is extremely fast, and certainly wouldn't be sustainable for months or even years. The highest level of exposure a person has to benzene is when they are pumping gas.
Erring on the side of caution is not a bad thing, but I don't think there is much to worry about.

ASH8

Agree with who, exactly??

IF you read what I said..

I am not the author of this information....just for discussion/interest.

Brettus

iTrader: (2)

Interesting - more weight to the argument of leaving windows open before starting the AC . I always thought that was just common sense anyway LOL

ken-x8

Hmmm. I almost always keep the ventillation system on "fresh," whether heating or cooling. The only exceptions are if it's really hot and the AC doesn't have the oomph, or if I'm driving through bad air like a dust storm or some industrial areas.

Ken

ASH8

Really Ken..?

No wonder so many complain of poor engine performance and cooling oomph when AC is on...forget the outside hot temps or outside warm, bringing in fresh warn or hot air in through the evaporator is just silly, your AC (Compressor) is trying to cool down outside air first before trying to cool the cabin, gee you might as well drive around with AC on and all widows fully open...

My S2 with Auto AC, if you turn it on will not allow you to use outside air to cool inside, will always default to recirc.

I think you will find all/most current new cars to be the same.

wow...

Loki

iTrader: (1)

Car interior plastics off gas, it's true. That's what new car smell is, and it is usually aromatic hydrocarbons. Whether its killing you or not..I'm sure they're not great..

If you open the windows and drive, i think you're breathing in some if the same compounds and some other worse things from exhaust and roadside particulates. Plastics offgas mostly when new, so if your car is over say 30000mi... Might be the lesser if 2 evils.

ken-x8

I don't really notice a performance drop when AC is on. AC gets wimpy when temperature approaches 100 F, and pretty much does nothing at that temp if I'm not moving. (Need to do the fan mod some day.) Recirc doesn't seem to help if it's 100 and I'm standing still.

I know there's an AC reprogram for early 8s that by default sets ventillation to recirc. I didn't know the S2s locked into that.

My wife's new Infiniti G seems content with ventillation set to fresh. The odd thing is that it likes to turn the AC on by default, even in the winter and even if defrost isn't selected.

Before I could afford to buy new cars I drove enough old clunkers with questionable exhausts that I really prefer to have fresh air coming into the car.

Ken

HiFlite999

iTrader: (2)

Wow, I run 99% of the time with fresh air intake + AC. And personally despise automatic climate control. Why? Because it often runs the AC at the same time as the mixer adds heat. While that keeps a more constant temperature, it keeps the AC compressor on much more than needed.

Far better to run the manual system with cabin air on "fresh", heat **** on full cold, and turn the AC on and off as needed.

There are very few occasions where the AC system is so loaded that it takes recirc to cool down the cabin. 37 C / 100 F kind of temps. (And I have a black car).

ASH8

Nope..you're totally incorrect ,

By running hot air through your AC Evaporator, you are just overloading system and getting very poor performance out of AC...and car.

No car maker recommends 'fresh air' with AC on to cool cabin particularly when over 30c...no one...I am not repeating what I already said, but no wonder most of you guys have issues with poor AC performance this is just nuts!, Compressor's running longer than usual, etc, etc..

I would not be surprised to see Evaporators icing up in some high humidity circumstances blocking/restricting cold air flow even more.

FRESH hot air flap open, air passes through Evaporator fins (what compressor freezes) trying to cool this hot air, then into vents/outlets into cabin.

On Recirc, Hot air intake flap is closed off and air is recirculated air flap open from cabin through Evaporator and then through vents/outlets after being cooled continuously, so it is way more efficient to cool down the air which is already being treated....do you cool your house with front and rear doors and windows wide open?

Any other way is just an unnecessary load on engine which is already boiling hot, trying to cool even hotter gas in Condenser in front of cars Radiator and extra load on Compressor, Fans, Alternator and then your MPG...stop and go traffic even worse.

For car Heater it does not matter as much as air is not being 'treated' apart from moving through the mini radiator (AFTER AC Evaporator) from engine coolant temps, using freezing cold air or recirc air will also result in different heater performance, but it is not being run by another loaded device.

Air mixing is not used above 30C..or should not be
.
And I use both fully Auto in RX-8 and manual AC in my MX-5, both systems have pluses and minuses.

But never would I put 45C (117F) fresh hot air like here today through my car Evap and expect good AC performance, or at temp above 30C.

I often wondered why so many AC Compressors were being renewed in US under warranty claims (it's well known in warranty talk)...some RX-8 guys are on their 4th Compressor in a few years!....there was a world shortage years ago for Mazda RX-8 'F151' AC DENSO Compressors (Also same in NB Miata).

HiFlite999

iTrader: (2)

Nope. I respectfully disagree. Perhaps some newer cars are "smarter" than old, but for all the ones I've had, when the AC is selected, the compressor runs essentially full time. Since I have a temp sensor in the lower radiator hose of my 8, I can directly monitor the heat load induced from the AC condenser: when the AC button is pushed on a warm day, the feed water to the engine goes up 5-10 deg F and stays there as long as that button is pushed, ie, the compressor never switches off in its own. I'll double-check this if/when it ever gets warm here again.

Cabin air temp is then controlled with the hot/cold mixing valve, so you end up heating the air you just cooled off. Leaving the manual temperature **** on full-cold shuts off any cooled air from flowing over the heater core. Heating AC cooled air is a fuel waster. When it gets too cold in the cabin, I switch off the AC.

You're correct that recirc can be more efficient, but only if the heat/cold **** is full cold. In most circumstances, that will not be true because it gets too cold inside, and people just turn that **** up toward "warm". If one leaves it on full cold and turns the AC on and off as needed, it becomes the more efficient mode. I'll have to try that this summer after my fuel totalizer is installed.

If there is a reason for an increased failure rate in the USA it's that most people here just adjust the cabin temp with the temp ****, leaving the AC on full time, and very few realize that the AC is on most any time the selector is set to defrost. (This isn't helped by the fact most manufacturers don't have the AC indicator light when defrost is on.)

Forced, as I was, to become an expert on my Audi's climate control system, I even hooked up a light to the AC clutch circuit to verify it indeed worked as I suspected it did. AC or Defrost "on" ==> compressor runs full time. Exceptions are with low or high system pressure, low OATs, or when the "bulb" sensor on the evaporator gets too cold.

In ~600,000 miles of driving, I've had one compressor failure and one clutch failure. With every one of my cars (except the RX8) I've always gotten above the EPA rating on the highway, except in very cold weather.

ASH8

Jeez M8, you are really starting to sound off.

First you have verified 'why and what' I am saying, AC Compressors in modern cars are NOT, repeat ARE NOT meant to 'run' all the time as you say, YOURS is ruining all the time because it can not cool down cabin air to thermostat levels because you are introducing fresh HOT air.

Compressor clutches are meant to cycle on and off about every 20 seconds, off for about the same and on again, all depends on cabin temps being lowered to, once at owners desired comfort level setting is reached, compressor turns on less.

Sorry M8, but adding in Hot outside Air to cool is just stupid.

IF an owner selects a warmer temp then on some occasions cars 'coolant heater' will operate (mixer), but this is AFTER the Evap, not before it, which is what you are doing by introducing HOT outside air before Evap.

Mazda's layout (like most cars)..
It is outside Air shutoff, interior FAN sucking inside air, Evaporator, Heater off/on, Outlets

And just for the record, I cant speak for AUDI or other brands, however given DENSO (Toyota) is used by Mazda, and that I have done a few training/install classes on AC and installs and have installed more than one AC @ dealer level (extra pocket money after hours) when Mazda Japan did not install AC's in Aussie new Mazda's for local tax reasons (imported as AC kit separately), nothing has changed that much...I even fitted a Diesel Kiki AC (genuine Mazda for 626 RWD Coupe then) to my own new car o the time.

Later

HiFlite999

iTrader: (2)

I don't have a thermostat set, only the manual **** (Series I). The cycling on/off every 20 seconds I count as on since that is it's more or less normal mode. Whether the heat from the mixer is added before or after the evaporator doesn't matter - it's still adding heat to the system airstream that is not there before. I conceded that 'recirc' is more efficient than vent air, but can be made more so by leaving the mixer full off (which can be done manually on my car, but cannot be directly controlled with a temp-set climate system.) As I said, I will try using the recirc mode more often in the future. I do use recirc under extreme conditions. Extreme to me in northern USA summertime is more likely to be normal where you live. Most of the time, even with the outside air vent open, the cabin gets too cold inside quite quickly. Can we at least agree that adding heat through the mixer is less efficient that simply turning off the AC until it's needed again in a few minutes?

ken-x8

That's interesting. I'll need to read the AC part of my owner's manual (and the one for my wife's G) more carefully. Not picking a fight...just chit-chatting...and maybe being a smartass...but that strikes me as manufacturers skimping on AC capacity at the cost of asphyxiating customers.

The only time I've had an evaporator ice up was on a VW Rabbit I owned back in the 80s. AC on that was really strong. It could raise goosebumps even on hot Virginia summer days. The drop in power when it kicked in was also very impressive. The AC **** on AMC Hornet my wife had in the 70s had a "Max" setting, and further to the right was a "Desert only" setting. Never felt over-cooled on any car since those two, so they've clearly been trimming back over the years.

FWIW, I keep cars a long time, and the only auto AC compressor I've had fail was on the Hornet. I put that down to it being an AMC product, not abuse on my part.

On the other hand, compressors on my house's heat pump seem to last an average of six years, and that's definitely a recirc system.

Ken

missinmahseven

Took an '84 GSL-SE (bought with 70,000) to 170,000, most of them with AC on fresh-air in the hot-and-humid SE US. Filter / dryer died at 140,000. Fixed it, sold it at 170,000. By that time all the rubber bushings, steering box, suspension were shot. Let the next owner worry about it.. but I still miss that car. Never should've sold her. Will find another GSL-SE one day. Cinco-Letras FTW!

Took a '94 Miata (bought new) to 160,000, most of them with AC on fresh-air. No AC troubles of any kind.

My '05 Shinka (bought new) has 131,xxx on her right now, most in SE Florida, with AC on fresh-air.. no AC problems.

The compressor cycles pretty much the same whether I run the AC on recirc or fresh air. The only times I use recirc are when outside temps are about 85*F and hotter or when in the vicinity of visible dust (construction, etc) or when I'm stuck behind a smoker's car (I used to smoke, and after quitting I find it revolting).

Both the Miata and RX-8 have systems that are somewhat less impressive than the old Freon systems. The GSL-SE's AC was a true chillin' machine.

None of my Mazdas ice over. The only car I've had that would ice over (no matter if in recirc or fresh air) was a '92 Mitsubishi Mirage the ex-wife had. It sure was a cold AC, though. Probably colder than the GSL-SE's.

And yes, I'm one that "mixes" during cooler weather -- to keep humidity down and keep the cabin from fogging up while having a nice cabin temp. Very rarely do I have to turn off the AC in SE FL. Usually by the time it gets down to 40%RH and 55*F-ish do I turn it off. This just doesn't happen very often here.

ASH8

Omg....

New Yorker

Sorry dude, but you're wrong:

2005 Owner's Manual, p. 6-6:
"It is recommended that under normal conditions the switch be kept in the outside air position.

Outside Air Position
Outside air is taken into the vehicle. Use this position for normal ventilation and heating.

Recirculated Air Position
Outside air is shut off. Air within the vehicle is recirculated.
This position can be used when driving on a dusty road or in similar conditions. It also helps to provide quicker cooling for the interior."

ASH8

'Normal" conditions, I guess it all depends on what one calls "normal"..

Some use their AC when it is not even hot....or car may have been in the sun, cabin is hot...whatever....but it is only 22C outside.

I am simply talking about HOT, repeat HOT summer conditions, ie above 30C (90F).

IMO 30C + is not Normal conditions...

As I said, I have installed many car AC's, they still (today) operate on the exact same principals, as do HVAC, or Ventilation Systems, Fresh and Recir Air....

You will never get past the fact that when you are bringing in hot air from outside you are passing this HOT air over your Evaporator which has a Temp Sensor inside of it...in the case of the RX-8 this sensor FE03-61-J22 is what monitors INTAKE Air Temps/Evaportator temp and controls Compressor on-off.

Go an ask any AC specialist and they will tell you you AC will always perform at its best on Recirc when it is over 90F.

New Yorker

I've read these same A/C instructions in every car I've had. Here in the US, at least, manufacturers all recommend using OUTSIDE AIR for general air conditioning. Which, in most parts of the country, means less than 90ºF most of the time. The idea, here, is that when your car has been parked in the hot sun for awhile and it's like an oven inside, you drive for a few seconds with windows open, then roll 'em up and start the A/C on RECIRC to cool it down quickly. Then… once you get to a comfortable temperature, you switch your A/C to OUTSIDE AIR.

Recirculate versus fresh-air: Tom and Ray settle one family's bet. On the line? A steak dinner. | Car Talk

RAY: "It's just that when you put it on recirculate, it recirculates the same cabin air (actually, it always lets in some fresh air). It takes the air it's already cooled down from inside the cabin and runs it through the evaporator again, making it even cooler. So in that sense, recirculate DOES cool the car more quickly.

TOM: On the fresh-air setting, the ventilation system brings in much more fresh, outside air, and cools that down. So it takes longer to cool the car that way. But, as you say, it does freshen the air, which might be important, especially if Daddy had one of Mom's bean-onion-garlic burritos for lunch.

RAY: So, recirculate does cool the car more quickly, but once it's cool enough, there's no good reason to leave it on recirculate. You can switch it to fresh air or keep it on recirculate -- whichever keeps you more comfortable."

ASH8

M8 you can keep posting 'quoted' and or 'recommended' sections until the cows come home, you know this subject can be a little bit like synthetic or dino oil 'recommendations'.....

From a mechanical point of view, and this is FACT.... and dare I say Dealers and particularly the complaints I see about US owners and poor AC performance with Mazda's is it any wonder...

ANY air conditioner that has to cool down HOT air continuously has to work harder to do so...
WHY, I should not really have to say this again.

If you are recirculating cabin air then it cools down much faster and requires less Compressor ON and therefore less load on it's Engine, it's cooling system, it's fuel consumption and electrical load....

YES, ALL the issues associated with recirculated air, like someone farting, dead fish in cabin, dead body and or body odor applies...blah, blah, blah.

It is NO different than running a AC system in your home (which uses compressors), if you have a hot day (90F +) with hot breeze do you leave a window or door open while trying to cool house down?

As I said, any car AC's will work less and is more efficient when on Recirc on HOT days.

Process the mechanics of same and you will have a better idea.

ken-x8

Nobody is disputing that. It's just that many of us, and whoever writes the owner's manuals that have been quoted, consider working the compressor harder to be part of the deal for cool non-toxic air.

Many of life's tribulations come down to that.

Ken

New Yorker

You know, I'm starting to think the difference in opinion might be cultural. Here in the US (with a few exceptions, i.e. Arizona, Texas, Florida, etc.), 90º+F temps are considered unusually hot, worthy of a story on the evening news. Summer temps in the 80's are more typical nationwide.

ASH8

80 or 90 is still hot...

If one finds Recirc air 'uncomfortable' for whatever reason, open your DS window a fraction (1/2 inch) and you get some 'fresh air' Recirc.

As far as Evaporators icing up, what do you think the pool of water on the ground is from after a car is off for awhile ?, the more water you have the more icing up of your Evaporator has occurred...the harder your Compressor is working, and AC is less efficient.

Having hot outside air blowing directly on any Evaporator when cooling is just backward.