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Discussion Starter #1
A guru A/C expert friend of mine insists that the recirculation function should be engaged at all times when the ambiant temps are...basically summer (hot), or humid. He makes strong arguements that recirculating cabin air puts much less strain on the AC system since that air has already been "fixed".

That said, it seems to me that the function is programmed backwards on all automatic HVAC systems I've seen.

My T&C would require that I disengage auto-climate to keep recirculate operating. Shouldn't the recirculate button be programmed to DISengage it? Otherwise, my auto-climate function's usefulness is negated.

Comments?

BTW, has anyone else had a problem connecting a freon gauge/filler to the low-side fitting? I can not get mine to connect using all my powers! The needle WILL depress though...with a screwdriver tip (don't tell anyone).
 

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When it's really hot use recirculate. If you have hay fever, use recirculate. On a rainy day, don't use recirculate.

I've had both auto and manual AC, and no matter what car, I like manual much, much better.

Regarding the low pressure connection, I haven't had to do anything on my T&C, but on my other cars, I will use a little saliva as a lubricant. Try it on another car and make sure it's not the connector on your gauge.
 

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A guru A/C expert friend of mine insists that the recirculation function should be engaged at all times when the ambiant temps are...basically summer (hot), or humid. He makes strong arguements that recirculating cabin air puts much less strain on the AC system since that air has already been "fixed".

That said, it seems to me that the function is programmed backwards on all automatic HVAC systems I've seen.

My T&C would require that I disengage auto-climate to keep recirculate operating. Shouldn't the recirculate button be programmed to DISengage it? Otherwise, my auto-climate function's usefulness is negated.

Comments?

BTW, has anyone else had a problem connecting a freon gauge/filler to the low-side fitting? I can not get mine to connect using all my powers! The needle WILL depress though...with a screwdriver tip (don't tell anyone).
He is right, keep the recirc on as much as you can.

And as far as the freon filler, are you trying to use one for R-12 and not R-134A? Have to use one for R-134A...
 

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I use recirc when i follow a stinky GM car or drive by a skunk, usually too late to help much in both cases.

But it makes sense to recool.... cool air vs bringing in hot!
 

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Mine's either broken or it was just that hot that day because I used the a/c with recirc on and didn't take the fan off full-speed for the whole hour's trip. Also, I thought the rear air was out because I had the rear heat lines closed off after they broke. I was told on here that the rear heat and a/c lines are separate so I did the same trip the next day using the rear a/c with the recirc off and after maybe 15 minutes the rear only needed to be on low and the front I was switching between 2nd and 3rd bump. It was only slightly cooler as well, 90 instead of 95.
 

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It really doesn't matter as long as you are comfortable. I don't use recirc unless I really need to as I like the idea of fresh air constantly being pumped in. Makes sure no odd smells build up on a hot day when a ton of sweaty people hop in. The a/c system does not care as it is going to pump the same amount of refrigerant through the condenser and evaporator no matter what.
 

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It really doesn't matter as long as you are comfortable. I don't use recirc unless I really need to as I like the idea of fresh air constantly being pumped in. Makes sure no odd smells build up on a hot day when a ton of sweaty people hop in. The a/c system does not care as it is going to pump the same amount of refrigerant through the condenser and evaporator no matter what.
Andy that's actually not true. The humidity is what is the difference. The A/C system removes humidity. If you live here in the very hot, humid south, you need to use recirc so the A/C system does not have to work as hard. Once you have the inside air cool, you can turn the blower down, and the freon has to do less which means the compressor can work less.
 

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Andy that's actually not true. The humidity is what is the difference. The A/C system removes humidity. If you live here in the very hot, humid south, you need to use recirc so the A/C system does not have to work as hard. Once you have the inside air cool, you can turn the blower down, and the freon has to do less which means the compressor can work less.
The compressor is locked solid to the belt whenever it is on. Since it is not variable, it will spin the same amount whether recirc is on or not, thus getting the same amount of wear. Unless you have auto temp control, then that will cycle the compressor less often when using recirc.
 

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Biggest problem with using recirc all the time is you can get mold growing inside the system from condensation forming and it stinks something horrible. I like the way the van is set to start on fresh air normally, and I can choose recirc only if it is really hot.
 

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The compressor is locked solid to the belt whenever it is on. Since it is not variable, it will spin the same amount whether recirc is on or not, thus getting the same amount of wear. Unless you have auto temp control, then that will cycle the compressor less often when using recirc.
Your right it pumps the same, but when the recirc is on, the evap stays colder, the freon stays colder, and the compressor has an easlier life... or at least that is what my A/C guy says...

To put it another way, the amount of freon pumped is the same, but the work the freon has to do is less.
 

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...I did the same trip the next day using the rear a/c with the recirc off and after maybe 15 minutes the rear only needed to be on low and the front I was switching between 2nd and 3rd bump. It was only slightly cooler as well, 90 instead of 95.
My understanding has been that rear a/c (or heat, for that matter) is always on recirc. Page 271 of my owner's manual has a caution box that says, "Interior air enters the Manual Rear Zone Climate Control system through an intake grille located in the passenger side trim panel behind the third seat. The heater outlets are located in the passenger side trim panel just behind the sliding door. Do not block or place objects directly in front of the inlet grille or heater outlets. The electrical system could overload causing damage to the blower motor." My assumption has been that this means the rear is always in recirc mode, and the button on the dash only applies to the front.
 

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Discussion Starter #13
The compressor is locked solid to the belt whenever it is on. Since it is not variable, it will spin the same amount whether recirc is on or not, thus getting the same amount of wear. Unless you have auto temp control, then that will cycle the compressor less often when using recirc.
That was my post's original intent.....you can't use auto temp control with recirc on. I would think that recirc would function with auto temp control but it doesn't. Or maybe that function can be reprogrammed to allow that???
 

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This may help.

I've been told that even in the Rec. mode about 10% of the air comes from outside anyway. If it didn't, then you would have a danger of inhaling exhaust fumes that might come into the cabin from a faulty exhaust system. (BTW, I had an Uncle die when he left the car running just to run into the Post Office to get his mail and a package. They found him in the P.O. parking lot with the car still running and an open letter in his hand.)

I copied this from an earlier post by Kyle in Newmarket, Ontario, Canada:
:ninja:

From the 2005 Caravan owner's manual (YMMV);

"The recirculation control is programmed to cancel the recirculation mode when the ignition key is turned OFF and will reset to outside air mode when the ignition key is turned ON....the recirculation mode can be programmed to not automatically reset to the outside mode by using the following procedures:
1. Turn the ignition switch to the OFF position
2. Set the mode control on the fan to "PANEL" (face/head).
3. Depress and hold in the "Rear Wipe/Wash" button.
4. Start the engine, and continue to hold in the "Rear Wipe/Wash" button until the indicator light starts flashing repeatedly.
5. Press the recirculation button until the indicator light remains lit.
6. The selection will be stored when the ignition switch is turned OFF or if the "Rear Wipe/Wash" button is pressed

If the recirculation indicator light is lit, the recirculation mode will not reset when the engine is started. If the recirculation indicator light is not lit, the recirculation mode will reset to the outside air mode when the engine is started. The programmed status can be changed back and forth by following the above mentioned procedure."

Kyle
Newmarket, Ontario, Canada
2005 Grand Caravan SXT
2003 Acura EL
1998½ Dodge Ram 2500 Quad Cab SLT Cummins Diesel 4x4(retired @7yrs/176K for '05 Caravan at wife's request )
1998 Honda CBR600 F3(The only thing from bachelorhood that the wife let me keep )
 

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I don't know if anyone else noticed with the auto temp controls, that if the inside temp is really hot, it'll automatically switch to recirculate until the temperatures come down, than it goes back to fresh air mode. The 3 zone ATC seemed pretty intuitive to me. I always hated using recirculate unless needed (super hot IN the car for a quick cool down, fowl outside smells, etc)
 

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This may help.

I've been told that even in the Rec. mode about 10% of the air comes from outside anyway. If it didn't, then you would have a danger of inhaling exhaust fumes that might come into the cabin from a faulty exhaust system. (BTW, I had an Uncle die when he left the car running just to run into the Post Office to get his mail and a package. They found him in the P.O. parking lot with the car still running and an open letter in his hand.)

I copied this from an earlier post by Kyle in Newmarket, Ontario, Canada:
:ninja:

From the 2005 Caravan owner's manual (YMMV)...


I found that in the owner's manual also, and was about to post it, then I re-read realized that the original post was specifically about the automatic climate control system. This passage from the owner's manual refers to the manual system. There doesn't appear to be an equivalent action you can take on the automatic system.
 

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Your right it pumps the same, but when the recirc is on, the evap stays colder, the freon stays colder, and the compressor has an easlier life... or at least that is what my A/C guy says...
jgbat - you're correct that the compressor's life is easier on recirc. The compressor spins, but once it has built up a high enough pressure difference between the low and high side, it consumes less energy and pumps less freon (this is true even of fixed-displacement compressors). This can be empirically verified by watching your instant-MPG trip computer number.

On recirc, the A/C becomes more efficient because the air being drawn through the system becomes less and less humid; and once it is cooler, it boils off less refrigerant.

Apparently, though, one disadvantage to the over-use of recirc is more potential for fungus buildup.

- G
 

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Apparently, though, one disadvantage to the over-use of recirc is more potential for fungus buildup.

- G
I agree the use of recirc does have benefits to its use, prolonged life of the compressor, quicker cool down of the interior.

There is one procedure I know of that takes a little occupant discomfort to help combat the fungal growth in the evaporator:
-Just before you stop and turn off the vehicle for a significant period of time, during the last mile or 2 minutes of travel to your destination turn off the A/C, switch to fresh air mode, have the fan level on medium to high. This will force what condensation is left in the evaporator to drain from the coils. I have been doing this in humid climates of central AL and south central NC with good results.

Like I said before, it will be just a tad warm in doing this. IMO a little discomfort is better than cleaning up the fungus or smelling that garbage while in the vehicle.
 
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