recirculation mode makes ac last longer?

[merconvvv]

Recirc dries out air pretty quick. I keep an humidity meter in car since mom got dry eyes.
Recirc is also most fuel efficient and cool efficient.


Pushing on buttons on cheap old dodge rubs against electrical connections behind them via the housing clips.
Go figure.

 

[Linctex]

Originally Posted By: Jetronic
You'd have a hard time sourcing a new car with a fixed displacement compressor.


Sorry, I think you're wrong for most of them.

The compressors are all still fixed displacement (as far as I know), but you are right in the "variable" part - - is the restrictor orifice that is wide open (no pressure differential) when the a/c isn't needed, and closes(allowing high side pressure to build) that cycles the A/C on modern cars.

The clutch stays engaged, yes - but the compressor just freewheels if it isn't needed because it isn't making pressure.

 

[Johnny2Bad]

Originally Posted By: motor_oil_madman
Oh I didn't touch the knobs, just the one button. I find it hard to believe that would wear out.


Haven't owned many Chrysler products, have you?

 

[DoubleWasp]

You don't have a Chrysler AC compressor, so I wouldn't worry about it.

Seriously though, I am not sure that it makes a huge difference one way or another.

You will notice the engine fan comes on more often when on fresh air, because the system is battling more heat. I am of the opinion that our trucks have marginal condensers due to space limitations. Converting from the factory tube-and-fin condenser to an aftermarket bar-and-plate condenser made a good difference for AC performance in my trucks.

Since one of my Rams went almost 300k on the original compressor (only the clutch bearing ever failed) and the other one knocked down 389k on its (preemptive replacement of working compressor out of concern for clutch bearing), I would not call these Ford compressors weak at all.

I think the hoses are the real "weakness". They felt like they were made of fiberglass resin when I swapped them out along with the compressors. Time and heat are not friends of rubber.

 

[CBR.worm]

Originally Posted By: Linctex
Originally Posted By: Jetronic
You'd have a hard time sourcing a new car with a fixed displacement compressor.


Sorry, I think you're wrong for most of them.

The compressors are all still fixed displacement (as far as I know), but you are right in the "variable" part - - is the restrictor orifice that is wide open (no pressure differential) when the a/c isn't needed, and closes(allowing high side pressure to build) that cycles the A/C on modern cars.

The clutch stays engaged, yes - but the compressor just freewheels if it isn't needed because it isn't making pressure.


No, most cars now (and many in 2006) have variable displacement compressors. They use a swash plate to change the piston stroke based on cooling requirements. Some newer cars (Audi comes to mind) don't even have a clutch, the compressor runs full-time.

 

[chrisri]

Originally Posted By: HerrStig
I've got a '99 Camry with 350,000 miles, running the AC about half the year. The AC has required nothing in that time but a R 134a top off. Perhaps running the recirc might make it last to what, 500? I suspect the parts quality is pretty good in that Generation Toyota. One cooling fan on these cars runs constantly when the AC is engaged, recirc or not, the compressor, of course, cycles less with the recirc engaged.


Funny I have a 99 FIAT Punto with 250K km (most city) and AC was only once topped off in all this years. Still working strong through whole year. Guess I'm lucky since it's Fiat.

 

[merconvvv]

" Originally Posted By: motor_oil_madman
Oh I didn't touch the knobs, just the one button. I find it hard to believe that would wear out.


Haven't owned many Chrysler products, have you?
"

+1. Just look on ebay for ac panel for your chrysler. Will give you an idea of what price replacement will cost and how bad is it for your year and model. I got one for ebay for 25 bucks but it does not look that nice but it does stop the car for going into default mode of bad ac panel. The computer will start blowing out hot air full blast out of defrost vent as if the car is possesed. Easy to replace them though so use the button as much as you like.
_________________________

 

[punisher]

Originally Posted By: chrisri
Guess I'm lucky since it's Fiat.


Probably the first, and likely the last time those words will be printed or spoken.

 

[InvalidUserID]

Slightly off-topic, but fan speed shouldn't matter to the AC system, correct? Whether I have the fan speed at the lowest setting or highest setting, the AC system works the same, right?

 

[Jetronic]

Originally Posted By: Linctex
Originally Posted By: Jetronic
You'd have a hard time sourcing a new car with a fixed displacement compressor.


Sorry, I think you're wrong for most of them.

The compressors are all still fixed displacement (as far as I know), but you are right in the "variable" part - - is the restrictor orifice that is wide open (no pressure differential) when the a/c isn't needed, and closes(allowing high side pressure to build) that cycles the A/C on modern cars.

The clutch stays engaged, yes - but the compressor just freewheels if it isn't needed because it isn't making pressure.


It's the stroke that gets changed by altering the angle of the swash plate

that changes the displacement.

 

[Jetronic]

Originally Posted By: InvalidUserID
Slightly off-topic, but fan speed shouldn't matter to the AC system, correct? Whether I have the fan speed at the lowest setting or highest setting, the AC system works the same, right?


It's working with different pressures (more fan speed heats the evaporator core more).

 

[WobblyElvis]

GM cars have had variable displacement compressors for some time now including my 06 Malibu.

 

[Tahoe4Life]

Originally Posted By: alex_at
turning the ac off to "dry" it before stopping: Exactly that behaviour made my system stink. My mechanic told me to keep the AC on all the time - since I do that no more stink.


I agree with this.

On my last vehicle left the A/C on constantly for 12 years and over 300K miles. Never shut the system off. There was zero stink. Some people that I know shut it off like some here have huge stink issues. On top of that their windows will fog up constantly when it is very humid out when they re start their car and turn the A/C back on again where as if you just leave the a/c on all the time it will not fog up when you start it back up. I leave mine on outside air all the time unless I get a smelly trunk in front of me in traffic.

 

[chrisri]

Originally Posted By: FORD4LIFE
Originally Posted By: alex_at
turning the ac off to "dry" it before stopping: Exactly that behaviour made my system stink. My mechanic told me to keep the AC on all the time - since I do that no more stink.


I agree with this.

On my last vehicle left the A/C on constantly for 12 years and over 300K miles. Never shut the system off. There was zero stink. Some people that I know shut it off like some here have huge stink issues. On top of that their windows will fog up constantly when it is very humid out when they re start their car and turn the A/C back on again where as if you just leave the a/c on all the time it will not fog up when you start it back up. I leave mine on outside air all the time unless I get a smelly trunk in front of me in traffic.

Me too although mechanics behind this doesn't seem logical. Vectra has a auto AC without normal button- one have to go through menu to start/shut the AC, so it's on all year. No odor, no humidity, all normal.

However with my other vehicles with manual AC (oldest is 1999,newest from 13) and with them I occasionally do turn off the AC before stopping. And when I do every time the smell and humidity is noticeable right after. So I just stopped bothering.

 

[WobblyElvis]

GM vehicles have a feature [usually hidden] in the BCM that can be accessed with a Tech2 scan tool. It's called "after blow" [no joke intended] and if activated it will run the cabin fan for a few minutes after shut down, with the ac system on, in order to warm/dry out the evaporated coil. I believe it's to prevent the formation of mould, and the resulting smell, from a damp air box.

My car doesn't have this feature so I shut down the ac 1/4 mile from home.
Is this helpful? I do not know.

 

[chrisri]

Originally Posted By: punisher
Originally Posted By: chrisri
Guess I'm lucky since it's Fiat.


Probably the first, and likely the last time those words will be printed or spoken.

For sure

. However it serves my needs and cost me nothing to keep it.

 

[merconvvv]

If its already in recirc mode the smelly truck should not effect you.
Sometime i switch to recirc mode if i see a car far ahead burning oil or big semi going up hills etc !

 

[gabriel9766]

My malibu has 2 a/c settings. Eco ac and regular ac. 99% off the time i run it on eco ac to "save gas" it says. Also normally i run it with the ac coming fun the outside air. If i run it on recirculation mode it keeps the cabin at a more steady temp. So keeping it on recirculation mode is more fuel efficient?

 

[Jetronic]

as soon as the interior temp drops below the outside temp, yes. just afterstarting, recirc isn't as fuel efficient if the car was parked in the sun.

 

[Shannow]

Recent New Scientist has an article on roadside pollution.

Reckons that on recirc, Particulate matter is reduced, while CO levels increase.

Just reporting what I read, not buying in.