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  #1  
Old 29th July 2010
Mr. Underhill Mr. Underhill is offline
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Default Low Pressure Port (to ReCharge AC with freon)

I've googled the heck out of this. I even took off my PS headlight and there is absolutely nothing resembling the low pressure port. Where exactly is this low pressure port. I have a 2002 9-3 SE. I feel so stupid. I'm all ready to roll with recharging this puppy and I can't friggin find this valve. Someone have any pics to show. Would be gggrreaaatttllluy appreciated.
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  #2  
Old 29th July 2010
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Quote:
Originally Posted by Mr. Underhill View Post
I've googled the heck out of this. I even took off my PS headlight and there is absolutely nothing resembling the low pressure port. Where exactly is this low pressure port. I have a 2002 9-3 SE. I feel so stupid. I'm all ready to roll with recharging this puppy and I can't friggin find this valve. Someone have any pics to show. Would be gggrreaaatttllluy appreciated.
I think it's behind the grill- very easy to remove.
Jack the car up and get under it with a light. You should eaily be able to identify the lines and follow them to the port.
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It really is that simple.
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  #3  
Old 29th July 2010
Oscuro Oscuro is offline
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It's right between the battery and the driver's side headlight. You do not have to remove anything except the plastic screw-on dust cap.
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  #4  
Old 29th July 2010
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99_9-3Mike 99_9-3Mike is offline
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Take a look at the engine side of the radiator, over by the battery.

See the little black cap? Take the cap off and there it is.

It's on a flange with the port pointing up.

Behind the grill is the high side port. Don't use that one to fill or top off.
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  #5  
Old 29th July 2010
Mr. Underhill Mr. Underhill is offline
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Default AC Low Pressure Valve -- FOUND IT!

Phew. I just found it. Thanks for responding so quickly. It was right in-front of the battery on the Driver Side. I think the one that is under the grill is the high-pressure port valve -- as it appears that that valve is bigger in diameter and wouldn't fit. It's funny, I pulled off the PS headlight and absolutely barren. While all along it was starring me in the face.

It appeared to work. I am just curious, if any one else out there has attempted to re-charge their freon (w/ R134a). This is what I did...

I undid the valve cap-- let the engine run for about three minutes.

I took a reading of the system-- got a reading of "just before the blue area" on the gauge.

Then starting pulling the trigger and shaking... for about 5 or so minutes.

The weird thing was...as this was going on, I heard my compressor kicking in ever so often (making a vrrrooooom vrooooom sound....something like that). I am not sure if that is normal though. To me, it appeared, like, when it made that kicking-in noise, it was sucking down the freon. Not sure. Anybody have any thoughts on this.

I forgot to release the trigger ever so often to take a reading, but when I realized that i forgot to do this, it read just at the top (or a little bit above) the blue area I guess that means it worked.

The can definitely felt lighter. I think I used 1/2 to 3/4 of a can (an 18oz can I believe).

One side note. My AC has been weak for quite awhile. (see post # 76 at
http://84.40.23.30/forums/showthread.php?t=50948&page=4 for more detail on this). One of the issues I had been experiencing was, if I got in my car with the AC on, it would go on... then almost like clockwork, after 3 minutes, AC would shut down completely (nada, nothing, no motor running whatsoever). Then, after 2 minutes, it would come on like nothing ever happen and continue to stay on. I just thought I'd throw that in for some background.


2002 Saab 9-3 SE Convertible
80K


This helped:
http://www.saabcentral.com/forums/sh...d.php?t=188239

This video also helped as well:

http://www.youtube.com/watch?v=B_XkaAHvgM0
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  #6  
Old 30th July 2010
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99_9-3Mike 99_9-3Mike is offline
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Quote:
"The weird thing was...as this was going on, I heard my compressor kicking in ever so often (making a vrrrooooom vrooooom sound....something like that). I am not sure if that is normal though. To me, it appeared, like, when it made that kicking-in noise, it was sucking down the freon. Not sure. Anybody have any thoughts on this."

The compressor will shut down if the pressure is too low or too high. Sounds like yours was too low. When the compressor comes on, it will suck down the can or cans. The system holds about 26 Oz total so you probably bought too much. Not a big deal since the can will hold it until you need it again. See how it runs and maybe add more if the compressor doesn't stay on.

Actually, I reread your post. If it's really high, the compressor will shut down as well. If it's cycling on and off now, it's probably got too much in the system. I suspect, if it's a little high, you'll get pretty good cooling now. Hopefully, it won't cycle on and off.

And hopefully, none of it will leak out....

Last edited by 99_9-3Mike; 30th July 2010 at 12:16 AM.
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  #7  
Old 30th July 2010
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I was planning on re-charging my A/C as well, since it went weak and finally quit last year, but I'm having some problems.

I bought a kit with the gauge, etc. I start the car up, set ACC to low. When I connect the gauge to the low-pressure port it reads 100psi. The compressor doesn't seem to be engaging at all. All fuses are ok. I ran a jumper lead from pin 30 to 87 on the A/C relay and this also doesn't seem to do a thing.

I'm not sure what I should do next. I assume the 100psi reading is since the hi/low pressures have equalized from not using the A/C for so long. Prior to stopping working the A/C was not very cold and came on and off intermittently, but there were never any sounds of bearings going bad etc.

Any ideas?
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  #8  
Old 30th July 2010
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Mine read 100 psi when the ECON mode was on. As soon as I turned it off, the compressor started and the pressure dropped to 25 psi. At that point, I added to 45 psi... Ron
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  #9  
Old 30th July 2010
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Quote:
Originally Posted by Slowparker View Post
I was planning on re-charging my A/C as well, since it went weak and finally quit last year, but I'm having some problems.

I bought a kit with the gauge, etc. I start the car up, set ACC to low. When I connect the gauge to the low-pressure port it reads 100psi. The compressor doesn't seem to be engaging at all. All fuses are ok. I ran a jumper lead from pin 30 to 87 on the A/C relay and this also doesn't seem to do a thing.

I'm not sure what I should do next. I assume the 100psi reading is since the hi/low pressures have equalized from not using the A/C for so long. Prior to stopping working the A/C was not very cold and came on and off intermittently, but there were never any sounds of bearings going bad etc.

Any ideas?
Is "low" the maximum AC setting?
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  #10  
Old 30th July 2010
Slowparker Slowparker is offline
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Ya ACC is set to "auto" and "low" with fan cranked. I'm going to go put the jumper from pin 87 to 30 and try measuring voltage at the red wire leading to the thermo switch on the compressor. It would be nice to hook up 12v direct to the compressor but I don't see an easy way to bypass the thermo switch. It's pretty tight down there.
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  #11  
Old 30th July 2010
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With pin 87 and 30 connected I'm measuring 12v at the connection to the red wire leading to the thermo switch. Any easy was to bypass the thermo switch and power the compressor directly?
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  #12  
Old 30th July 2010
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I ran power direct to the compressor and which kicked in nicely. A/C running nice and cold in the cabin. Refrigerant pressure within spec.

Is the likely culprit the thermo switch on the compressor?
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  #13  
Old 30th July 2010
busaboy busaboy is offline
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There are low- and high-pressure switches, as well, aren't there? One or two of those might be bad...
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  #14  
Old 30th July 2010
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I just went and measured 12v before the thermo switch, with A/C relay in place, nothing bypassed. So I'm thinking it must be a dead thermo switch...
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  #15  
Old 2nd August 2010
Mr. Underhill Mr. Underhill is offline
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Default AC Still Not So Cold

Quote:
Originally Posted by 99_9-3Mike View Post
Quote:
"The weird thing was...as this was going on, I heard my compressor kicking in ever so often (making a vrrrooooom vrooooom sound....something like that). I am not sure if that is normal though. To me, it appeared, like, when it made that kicking-in noise, it was sucking down the freon. Not sure. Anybody have any thoughts on this."

The compressor will shut down if the pressure is too low or too high. Sounds like yours was too low. When the compressor comes on, it will suck down the can or cans. The system holds about 26 Oz total so you probably bought too much. Not a big deal since the can will hold it until you need it again. See how it runs and maybe add more if the compressor doesn't stay on.

Actually, I reread your post. If it's really high, the compressor will shut down as well. If it's cycling on and off now, it's probably got too much in the system. I suspect, if it's a little high, you'll get pretty good cooling now. Hopefully, it won't cycle on and off.

And hopefully, none of it will leak out....
Thanks for the insight. My guess was that cycling was the car sucking up the juice. I do think I put to much into it. That being said... not all that much of a difference in coldness. But then again, I was having AC issues long before I did a (attempted a) re-charge.

I'm just a bit bewildered b/c I've had my resistor and blower replaced twice prior and that starting...off for 2 minutes...then started back up (yet blowing weak as heck) still remains. My hunch from all this talk is that it may be something electrical. I'm bringing my car in for oil and such... I'll ask them for their insight. Last time was hooked up to tech thingy...passed with flying colors. That be-wilders me even more...why doesn't the computer recognize something is wrong. Grrrr. I'll keep you posted if I get any insight.
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  #16  
Old 6th August 2010
jjthegreat jjthegreat is offline
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Just so you guys know, you should take the the low side pressure reading when the compressor is OFF. When the compressor runs, the low side will drop quite low, to less than 15 psi, this is fine. Add some r134 when the compressor is running, then stop it, wait a minute and take a reading. if it goes higher than 60 psi, you have too much in there. if you set your cooling to max, the compressor will need to run continually.
for fun rev the engine to 3500 while in your driveway. if it cycles off, then on again, the high pressure switch is kicking in.
too much doesnt help either boys, ive made this mistake and posting my results here heh.
//JJ
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  #17  
Old 7th August 2010
busaboy busaboy is offline
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One does NOT check operating pressures with the compressor "off!".
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  #18  
Old 7th August 2010
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Quote:
Originally Posted by busaboy View Post
One does NOT check operating pressures with the compressor "off!".
With the system off, the pressure on both high and low sides will equalize.

So I guess you would be measuring total system pressure and assuming it's all freon.

Given this, 60 does seem high and this seems to be a useful measurement to me.

Just my 2 cents.
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  #19  
Old 8th August 2010
busaboy busaboy is offline
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While I'm no AC mechanic, I'm not sure that's a useful piece of information. My reference materials for residential and automotive AC has never discussed the static pressure of an AC system.
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  #20  
Old 8th August 2010
jjthegreat jjthegreat is offline
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I did some more looking into it, and really the best way of doing things is attaching a gauge to the hi pressure side as well. in my case, adding refrigerant to the point of having 25 psi on the low side, caused the compressor to cut out once I hit 3000 rpm. worked fine in idle.
I bled out quite a bit thru the low side port until the compressor ran continually at all rpm ranges, unfortunately, i dont own a gauge for the hi side port, and dont forsee myself spending money on one either
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