AC - Does it really sap that much power? - SaabCentral Forums
* site search:  
Home Saab Pictures Saab Classifieds Saab Dealer Listings Saab Forum Saab Forum

Go Back   SaabCentral Forums > Saab Classic 900, 1979-1993 & '94 Convertible > Saab Classic 900 Workshop
Saab Classic 900 Workshop Classic Saab 900 (1979-1993 & '94 Convertible) Technical Forum.

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 9th February 2007
jameschong's Avatar
jameschong jameschong is offline
Saab Crazy
 
Join Date: Feb 2006                                                
Location: Singapore
My Saabs: '90 LPT to FPT, auto to 5sp type 8
Posts: 941
Default AC - Does it really sap that much power?

Does your c900 seem to sap significant power when the compressor is engaged?

I'm starting to turn the aircon compressor off when I want more power. This is not good.

I'm wondering if this is to be expected, or if it's a sign of something going wrong....
__________________
"I will never join a club that accepts people like me as members..."
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2  
Old 9th February 2007
grif900's Avatar
grif900 grif900 is offline
Saab Lunatic
 
Join Date: May 2006                                                
Location: W. Yarmouth,MA. U.S.A.
My Saabs: 1988 900 SPG
Posts: 4,358
Default

a.c. pump when engaged uses a lot of kw(hp). and c900s are not known for having much to spare, so the difference is very noticable. id say normal.
Reply With Quote Quick reply to this message
  #3  
Old 9th February 2007
900t's Avatar
900t 900t is offline
Saabista
 
Join Date: Dec 2002                                                
Location: Montreal, Canada
My Saabs: 1989 900t, 1990 900t, 1990 900 S, 87 SPG
Posts: 18,247
Default

At WOT it turns off...

Just imagine if you had an old 62 horsepower Benz 240 D with the super power sucking reciprocating-piston York A/C compressor
__________________
Turbo allows the valiant who has appeared at the wheel SAAB to gain momentum for 200 km/h Charm SAAB Turbo also that it to you not bad Porsche on it it is possible with speed of pregnant turtle feeling itself in full comfort which by the way our hero obeys a rudder reliably and confidently the truth management hardly will twirl a steering wheel by one finger uneasy. Without the hydraulic booster quickly enough perishes a steering shaft, but to change its hemorrhoids from the most fierce
Reply With Quote Quick reply to this message
  #4  
Old 10th February 2007
grif900's Avatar
grif900 grif900 is offline
Saab Lunatic
 
Join Date: May 2006                                                
Location: W. Yarmouth,MA. U.S.A.
My Saabs: 1988 900 SPG
Posts: 4,358
Default

i used to have a 240 with a four speed manual trans.,we called it our luxury farm tractor and after i fixed the a.c. we just called it cool.but , driving it took planning,like when trying to pull out into a buisy roadway.or any other seemingly normal move.with the a.c. on i reckon it had about 7 weasel power.
Reply With Quote Quick reply to this message
  #5  
Old 10th February 2007
skilpadda's Avatar
skilpadda skilpadda is offline
Senior Member
 
Join Date: Feb 2004                                                
Location: Mosjoen, Norway
Posts: 242
Default

I dont notice any difference in performance on my 91 900s when I run the ac. Only a slightly higher fuel consumption(8-10%).
__________________
`78 99 T
`87 900 T16 "Aero" cab. (my wifes)
`91 900S
`78 MF 148 4wd

99T project-http://www.saabcentral.com/forums/sh...ad.php?t=84245
Reply With Quote Quick reply to this message
  #6  
Old 10th February 2007
TheRedBaron's Avatar
TheRedBaron TheRedBaron is offline
Saab on the Brain!
 
Join Date: Aug 2006                                                
Location: Washington, DC
My Saabs: 1990 900 turbo
Posts: 5,779
Default

Every car I've ever driven has performed worse with the AC on...unfortunately I can't comment on the c900 because I won't have AC on mine till the spring (for $280 including labor at the place I bought it from on stipulations of the selling contract!)
__________________
The faster you go, the more you see.
Reply With Quote Quick reply to this message
  #7  
Old 10th February 2007
woywitka's Avatar
woywitka woywitka is offline
Guest
 
Join Date: Jul 2004                                                
Location: North Vancouver, British Columbia, Canada
My Saabs: '87 900 T16 vert, 911 SC,914,W123 Diesel
Posts: 7,035
Default

yeah I notice it. If your running r-12 you shouldn't notice much, but since r134A takes tremendously more power to compress the gas it sucks LOTS of power.
Reply With Quote Quick reply to this message
  #8  
Old 10th February 2007
TheRedBaron's Avatar
TheRedBaron TheRedBaron is offline
Saab on the Brain!
 
Join Date: Aug 2006                                                
Location: Washington, DC
My Saabs: 1990 900 turbo
Posts: 5,779
Default

Quote:
Originally Posted by woywitka
it sucks LOTS of power.
Guess when I get my AC done I'll have to mod my car s'more to make up for it!!
__________________
The faster you go, the more you see.
Reply With Quote Quick reply to this message
  #9  
Old 10th February 2007
woywitka's Avatar
woywitka woywitka is offline
Guest
 
Join Date: Jul 2004                                                
Location: North Vancouver, British Columbia, Canada
My Saabs: '87 900 T16 vert, 911 SC,914,W123 Diesel
Posts: 7,035
Default

Quote:
Originally Posted by TheRedBaron
Guess when I get my AC done I'll have to mod my car s'more to make up for it!!
won't help, it is off the line that is sucks, once boost hits or i'm on the freeway I don't notice it much.
Reply With Quote Quick reply to this message
  #10  
Old 10th February 2007
Jim Mesthene Jim Mesthene is offline
Saab on the Brain!
 
Join Date: Feb 2006                                                
Location: New England
Posts: 9,468
Default

Jaguar XJ6 A/C systems were 36,000 BTU.
Assuming the SAAB's is smaller, say 25,000 BTU, you can expect it to use abot 10kw (15 horsepower?) at full load. That's why there's a full throttle switch that turns the compressor off when the throttle is wide open.
So, the answer is: yes, it uses a lot of power; no, it doesn't slow you down.
__________________
Double your money back if my advice doesn't work!
Reply With Quote Quick reply to this message
  #11  
Old 10th February 2007
woywitka's Avatar
woywitka woywitka is offline
Guest
 
Join Date: Jul 2004                                                
Location: North Vancouver, British Columbia, Canada
My Saabs: '87 900 T16 vert, 911 SC,914,W123 Diesel
Posts: 7,035
Default

Well the other issue with the Saab system is that it was designed to run r-12, and I'm told it is brilliant with r-12; however, r-12 burns holes in our ozone and we must run r134a. R134A operates at much higher pressures and takes twice as much energy (or more) to produce a fraction of the cooling ability of r12. That is why our A/C sucks with r134A, it is "cool" but not "freezing".

The power loss with r-12 I was told by older Saabnuts was barely detectable, and when the compressor cut in when you were relasing the clutch it wouldn't screw you up.
Reply With Quote Quick reply to this message
  #12  
Old 10th February 2007
cdaly's Avatar
cdaly cdaly is offline
Moderator
 
Join Date: Dec 2003                                                
Location: Dublin, Ireland
My Saabs: '92 900LPT, '90 900i vert
Posts: 4,637
Default

Quote:
Originally Posted by jameschong
I'm starting to turn the aircon compressor off when I want more power. This is not good.

I'm wondering if this is to be expected, or if it's a sign of something going wrong....
I wonder is your Throttle Position Switch not working? There should be a pair of contacts that are shorted when at WOT and open otherwise.
Reply With Quote Quick reply to this message
  #13  
Old 10th February 2007
Jim Mesthene Jim Mesthene is offline
Saab on the Brain!
 
Join Date: Feb 2006                                                
Location: New England
Posts: 9,468
Default

Quote:
Originally Posted by woywitka
Well the other issue with the Saab system is that it was designed to run r-12, and I'm told it is brilliant with r-12; however, r-12 burns holes in our ozone and we must run r134a. R134A operates at much higher pressures and takes twice as much energy (or more) to produce a fraction of the cooling ability of r12. That is why our A/C sucks with r134A, it is "cool" but not "freezing".

The power loss with r-12 I was told by older Saabnuts was barely detectable, and when the compressor cut in when you were relasing the clutch it wouldn't screw you up.
I'm not a SAAB nut, but I'd worked on R12 systems for 20+ years before R 134a came along. 900s always had weak A/C, not brilliant.
Pressures are only a little higher with134a. With a larger condenser, performance is about the same, with the old condenser retrofitted with 134a, you need more airflow; pressure can rise in traffic.
I never noticed any difference in power loss (although, theoretically there should be some).
In traffic 134a is lame instead of barely adequate, at speed, there's not much practical difference.
__________________
Double your money back if my advice doesn't work!
Reply With Quote Quick reply to this message
  #14  
Old 10th February 2007
900t's Avatar
900t 900t is offline
Saabista
 
Join Date: Dec 2002                                                
Location: Montreal, Canada
My Saabs: 1989 900t, 1990 900t, 1990 900 S, 87 SPG
Posts: 18,247
Default

If you think R134a sucks, wait until R134a is banned, as the EU is doing in 2011... global warming...

They want to use CO2 as a refrigerant, but it takes like 5x the pressure of R134a
__________________
Turbo allows the valiant who has appeared at the wheel SAAB to gain momentum for 200 km/h Charm SAAB Turbo also that it to you not bad Porsche on it it is possible with speed of pregnant turtle feeling itself in full comfort which by the way our hero obeys a rudder reliably and confidently the truth management hardly will twirl a steering wheel by one finger uneasy. Without the hydraulic booster quickly enough perishes a steering shaft, but to change its hemorrhoids from the most fierce
Reply With Quote Quick reply to this message
  #15  
Old 10th February 2007
GearHead's Avatar
GearHead GearHead is offline
Saab Lunatic
 
Join Date: Jul 2003                                                
Location: Lewiston,Idaho,USA
My Saabs: No current saabs :(
Posts: 3,824
Default

what about propane?
__________________
SAAB: Its an Addiction
Reply With Quote Quick reply to this message
  #16  
Old 10th February 2007
900t's Avatar
900t 900t is offline
Saabista
 
Join Date: Dec 2002                                                
Location: Montreal, Canada
My Saabs: 1989 900t, 1990 900t, 1990 900 S, 87 SPG
Posts: 18,247
Default

It's great but for some reason people don't like to put 500 grams of propane in their car, even though there is 50 kg + of gasoline in there too Apparently window-mount air conditioners for homes in Europe are going to start using propane though which is surprising. I guess the Europeans like to live a bit more dangerously than us North Americans.
__________________
Turbo allows the valiant who has appeared at the wheel SAAB to gain momentum for 200 km/h Charm SAAB Turbo also that it to you not bad Porsche on it it is possible with speed of pregnant turtle feeling itself in full comfort which by the way our hero obeys a rudder reliably and confidently the truth management hardly will twirl a steering wheel by one finger uneasy. Without the hydraulic booster quickly enough perishes a steering shaft, but to change its hemorrhoids from the most fierce
Reply With Quote Quick reply to this message
  #17  
Old 10th February 2007
jameschong's Avatar
jameschong jameschong is offline
Saab Crazy
 
Join Date: Feb 2006                                                
Location: Singapore
My Saabs: '90 LPT to FPT, auto to 5sp type 8
Posts: 941
Default

I'm still allowed to use R-12 in Singapore, since the car was registered before legislation banning R-12 came into force.

The TPS, temperature and pressure sensors work to cut the compressor off and restore power. But it's non-WOT conditions that make the power loss bad. As well as vibration and a drone which I think it from the belt under tension.

The compressor itself works well, delivering the pressure (I just had it checked recently). But the location of the evaporator, on the "hot" (or right) side of the engine bay doesn't help.

The AC cools the car marvellously when it's going at highway speeds and the engine isn't hot. When it's in stop/start traffic, it barely cools.

And it doesn't help with the black fabric roof under the mid-day sun in the tropics....
__________________
"I will never join a club that accepts people like me as members..."
Reply With Quote Quick reply to this message
  #18  
Old 11th February 2007
cdaly's Avatar
cdaly cdaly is offline
Moderator
 
Join Date: Dec 2003                                                
Location: Dublin, Ireland
My Saabs: '92 900LPT, '90 900i vert
Posts: 4,637
Default

If there was not enough gas in the circuit, you wouldn't get good cooling except at high engine revs. Is there a sight glass on top of the receiver? If so, you should see bubbles in this just after the compressor cuts in and they should clear away after a few seconds. If they persist or only go away under high revs, you're most likely low on gas.
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:
If you do not want to register, fill this field only and the name will be used as user name for your post.
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 07:48 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.