air conditioning system question - SaabCentral Forums
*
Home Saab Pictures Saab Classifieds Saab Dealer Listings Saab Forum Saab Forum


Go Back   SaabCentral Forums > Saab Cafe > The Lounge

The Lounge For general discussions

SaabCentral.com is the premier Saab Forum on the internet. Registered Users do not see the above ads.
Reply
 
Thread Tools Display Modes
  #1  
Old 17th September 2004
Cojoroh Cojoroh is offline
Saab Lunatic
 
Join Date: Sep 2003                                                
Location: Raleigh, NC, USA
My Saabs: '04 Saab 9-3 Linear MT
Posts: 1,234
Default air conditioning system question

i'm posting this question in the lounge because i posted this same question in the SS forum a while back but hardly got any responses. i don't know much about air conditioning systems, but it is my understanding that the climate control system uses freon in combination with heat from the heater core to achieve a certain temperature through the vents. my question is, (1.) what settings will use the least amount of gas, (2.) and what settings will use the least freon? i usually leave the temperature at the coldest setting and reduce the fan speed if necessary...but i've seen many people raise the temperature setting to save gas...does this actually save gas, or is it just mixing heat with the cold incoming air? also, i think the new variable displacement compressor used for the new SS may change the equation here. can anyone answer my questions?
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2  
Old 17th September 2004
Rob in Atlanta's Avatar
Rob in Atlanta Rob in Atlanta is offline
Saab Lunatic
 
Join Date: May 2004                                                
Location: Brookhaven, Atlanta, Georgia, USA
My Saabs: '98 900S/ '06 9-3 Aero
Posts: 1,611
Default Re: air conditioning system question

Quote:
Originally Posted by Cojoroh
my question is, (1.) what settings will use the least amount of gas
The most efficient setting is one where the air conditioning compressor does not need to run. When the compressor runs, it produces drag on the engine. The engine must produce more power, thereby using more gas, to operate the car at the same speed. If you only use fresh air, either unheated or heated, then you should be using the most efficient setting on the climate control system.

Quote:
Originally Posted by Cojoroh
(2.) and what settings will use the least freon?
1. The climate control system in the Sport Sedan (and in the earlier NG 900) uses R-134a refrigerant instead of freon.

2. Regardless of the type of refrigerant used by the air conditioning system, it is not "used" up or consumed by running the system. The refrigerant is in a "closed loop" system and is constantly recycled. The refrigerant acts only as a heat transfer medium. It absorbs heat in one part of the system and releases it in other parts of the system. Essentially think of the air conditioner as a heat pump. It pumps heat from the interior of the car to the exterior. It constantly performs this cycle. The only way that refrigerant, R-134a, Freon or some other refrigerant, is lost is through a leak in the system. N.B. Conventional wisdom instructs us that using your air conditioning system more probably helps to prevent leaks because it keeps the seals well lubricated and tight.

Quote:
Originally Posted by Cojoroh
i usually leave the temperature at the coldest setting and reduce the fan speed if necessary...but i've seen many people raise the temperature setting to save gas...does this actually save gas, or is it just mixing heat with the cold incoming air? also, i think the new variable displacement compressor used for the new SS may change the equation here. can anyone answer my questions?
I'm not certain as to how the variable displacement compressor interacts with the need for cooling power, so I can't really address this part of your question. Raising the temperature may in reality only add heat to otherwise already cooled and conditioned air. In that case, raising the temperature might have little or no effect on gas mileage. Maybe someone else knows more about the variable displacement aspect of the compressor and how outlet temperature is regulated.

Rob in Atlanta
'98 900S, 5-Door, Manual, 168K miles
Reply With Quote Quick reply to this message
  #3  
Old 17th September 2004
Stefano's Avatar
Stefano Stefano is offline
Saab Mad
 
Join Date: Jan 2003                                                
Location: Ducatiland (Bologna-Italy)
My Saabs: 2 9ks,white '87T &'96 Silver Aero 2.0
Posts: 3,053
Default

In fixed-displacement compressors systems, the desired temperature is achieved turning on the system when the air is hotter than the desired temperature range, and turning it off when it's colder (of course the temp range is no large rthan a couple of degrees).So when you say

Quote:
but i've seen many people raise the temperature setting to save gas...

it can be true if it's to save gas intended as fues, not freon. If the temp is higher, the times the compressor is engaged will be shorter than those in case the temp was lower (I hope I'm clear enough....) so the engine, having to drive the compressor for less time, will burn less fuel eventually. But it's not about Freon consumption, as Rob saied. Freon is only comsumed by leaks.



You saied

Quote:
it is my understanding that the climate control system uses freon in combination with heat from the heater core to achieve a certain temperature through the vents.


The heat from the heater core is not used for that, it's only if you want to heat up the car and defog the windshield that they system turns on the A/C because the cooling that the air receives alloews to moisture to condensate and thus to separate so the air, after being heated, is dry and can successfully defog the glasses. But this combination is only used to defog, as far as I know (I'm sure about my 9000).


Variable displacement systems...... as far as I know, they reduce their displacement when the temp required isn't too cool, so instead of angaging and disengaging all the dime, they just stay engaged all the time but they pump less. This way you avoid mechanical stress, you have a more constant temperature and engine load.

Hope this makes things clear. Please ask if I wasn't clear, I'm not sure I was but I can explain better if you need.
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Bookmarks

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the SaabCentral Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Display Modes

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 04:10 AM.



Powered by vBulletin® Copyright ©2000 - 2014, vBulletin Solutions, Inc.

top of page | sitemap | email us



copyright © 2003 - 2011 saabcentral.com, All rights reserved http://www.whiter.co.uk - valid xhtml - valid css
SaabCentral is an independently run website and is not affiliated in any way to Saab Automobile AB.


Garage Plus vBulletin Plugins by Drive Thru Online, Inc.